Simply complete the training level, very easy.

PLEASE NOTE, THE GAME MUST BE COMPLETED ON EACH DIFFICULTY SEPERATELY FOR THE ACHIEVEMENTS!

Complete the whole game, on Professional difficulty. Complete this however you like, with whatever ratings / weapons you want. Just get to and complete Ammendment XXV

Gameplay Video Walkthroughs for all levels for use on completing the game - All credit to Elil of Hitman Forums

A Vintage Year - Youtube link

Curtains Down - Youtube link

Flatline - Youtube link

A New Life - Putfile link

The Murder of Crows - Youtube link

You Better Watch Out... - Youtube link

Death On The Mississippi - Putfile link

Till Death Do Us Part - Youtube link

A House of Cards - Putfile link

A Dance With The Devil -
Part 1 - Youtube link
Part 2 - Youtube link

Amendment XXV - Youtube link

Requiem - Youtube link

Upgrade Custom Weapon Achievement Cheat/Glitch - Full credit to s1u5h13

I have edited it a little and made the grammer a touch better
Alright save up around 1.6 mill or so, then save.

Enter any level, im gonna pick "Till Death Us Do Part" or "A New Life" since they are the shortest. Goto upgrade weapons, upgrade any weapon you want to 100%, buy every upgrade you can, only for that 1 weapon then start the level, complete it, then you'll get the achievement for the weapon you fully upgraded. Shut off your console before saving! or continuing. DO NOT SAVE! If you then restart your console, and load your save game, you will still have all your cash, minus the upgraded weapon, but still holding the achievement you had just gained! Repeat as above but upgrading a different weapon each time, and you will be able to gain all the achievements for each gun, without having to earn enough money to do them all at the same time!!

Can be done on any difficulty, or spread out over multiple difficulties.. (achievement is given as soon as the weapon is upgraded and a level completed, not once all are upgraded at the same time)

Simply fully upgrade the weapon (requires all the Kruger Schmidt upgrade tiers be unlocked) Once upgraded, play through and complete the level for the achievement to be unlocked.

Collect all the guns in the game (which can be retained in the Hideout, Not all guns can be). Collect a gun by finishing a level with the particular weapon in your possession. You can take as many weapons at a time out of the level as you wish (you can only carry one rifle at a time).
You can go back and re-do a level at any time, and reply that level as many times as you like, and each time you complete it, any new weapons you bring out which aren't currently in your hideout will be added.

Please note each difficulty settings has its own seperate hideout. You only need fill one hideout to gain the achievement. This can be done on any difficulty setting you wish.

List of guns (with hideout images) and locations - Full credit goes to [TFU]Shakey of the hitmanforums for names and images, locations taken from everyone within the weapons thread stickied in this forum!

Bull .480 - SLP .40 S
Snub nose - Six shooter - Desert eagle - SLP .40

MP9 - MP5
TMP - SAF SMG
MP7

Shotgun
M14

SG552 - FN2000
Air Rifle

W2000
M4

SPAS 12
Ballers - SMG Tactical

Dragunov
Elephant Rifle - Kazo TRG

Weapon Locations
Credit to the stickied post within this forum and everyone inside it

MP7
Numerous Levels (The guards in black suits on the level "Requiem" namely)

Desert Eagle
Numrous Levels ("A Murder Of Crows" being one) Also found on the table when you enter the room to duel with the devil bartender/assassin on the level "A Dance With The Devil"

Shotgun
Numerous Levels ("A Vintage Year", "Till Death Us Do Part" etc)

Six Shooter
All over the level "Till Death Us Do Part"

Bull.480
Vinnie in "A New Life" has one

SLP.40 Pistol
Everywhere

Snub Nosed
The General (The father wearing a white suit who plays the chello) is carrying one when you kill him on the level "A Vintage Year"

SLP.40.S
The female target wearing a black guard suit (wandering the map with the walkie talkie on "A Murder Of Crows")

SAF SMG
Found on the High Security guards on "A Vintage Year" (one is in the room with the sleeping guard and the guard suit)

TMP
Rehab Centre or Manuel Delgado has one in "A Vintage Year"

MP5
CIA agents have them, if I got this wrong, Maynard John (The devil bar tender / assassin) has one on the "A Dance With The Devil" level when you kill him

M14
US Army have them in the Whitehouse

FN-2000
CIA Agent (In yellow/gold suit) is carrying it when he enters the lift (It is inside a case) on the level "A dance with the devil"

M4
Yours Already

W2000
Yours Already

Silverballers
Yours Already

SP-12 Shotgun
Yours Already

SMG Tactical
Yours Already

KAZO TRG
Sniper (Raymond on "A Murder of Crows" has it, this is the sniper bird suit guy)

SG552
Mark Purayah Jr on Murder with Crows has it, this is the guy which recieves the diamonds case

MP9
Yellow Feathered Bird Guards in " A Murder of Crows"

Air Rifle
Tree House on the level "A New Life"

Elephant Rifle
Sniper on the wall of Pappy's Room in "Till death us do part"

Dragonov
"A dance with the devil" level, found by the table (inside a case, you can just carry the case out with you with the gun still inside no problems btw) with the laptop on which you have to search to get the info

I will list ways of achieving the silent assassin rating on Professional Difficulty only (As this has the most level completion requirements) and 5 random maps only, as this is all that is needed to get all 4 of the silent assassin achievements. Obviously the lower the difficulty, the less needs to be done to get the rating.
Killing all targets via accidents, hiding any civilian bodys (for suits etc) after only sedating or knocking them out, no cover blown, suit not left behind, no witnesses, and no custom weapons left behind will pretty much guarentee Silent Assassin.

Use these in conjunction with the video walkthroughs, on the PC it seems you don't need accidental kills to get the silent assassin achievement, and I think I did, so just follow the walkthroughs, and use the stuff below to get the accidental kills.

Mission 2 - A vintage Year

Kill Don F.Delagado - The Don is playing his chello upstairs / moving to his balcony to look at the view. Personally I go up there through the window. While he is playing, creep accross the back of the room and get in the closet. When he has finished playing, he will get up, walk past you (in the closet) and into the next room and to his balcony. Follow him (while creeping). The guard in the sette next to him is asleep, so long as you creep neither will know you are approaching. Sneak up behind the down and push him over the railings of his balcony.

Kill Manuel Delgado - Just inside the entrance to the wine cellar from the main courtyard with the public in, there is a guard standing aside a winch. Approach the guard and he will start going on his patrol down the stairs. When he is down at least 1 flight of the steps, plant the bomb.

Its now a game of timing to set off the charge under these circumstances:
- No one (Guard or public) are on the landing where the winch is, if there are, then you will have casualties
- Manuel is stood in the little nook at the bottom of the stairs (Be careful, sometimes he is talking to someone, you need to hit the trigger while he is there alone, he ussually ties his shoelace)

Mission 3 - Curtains Down

Kill Alvaro D'alvade - At the begining of the level, goto the cloak room / reception and talk to the guy behind the counter, he will give you your coat of which you take out a WWII gun. Get into the stars dressing room while the rehersals are in progress (the room in the middle of the corridor with a star outside it, not the one directly infront of the one with the guard sat down) and wait for the guy to come back during there break. Hide in his closet. He will mess around a bit and then leave to goto the toilet. At this moment, get out the closet, take his replica gun which he has left on the table, place the real WWII gun and get back in the closet. Once he has returned and left again with the real gun. Leave the room.

Kill Richard Delahunt - After planting the gun, directly outside his dressing room, are a set of double doors. Go through them and take the stairs right to the top. This leads ou above the stage. Go around the stage gantry and through the door. Approach the winch in the centre of the walkway and place the bomb (at this point I continue down the walkway passed the winch and down the ladder following the walkway around the dome to the hole in the floor. Go down the hole and sit waiting for the accidental shooting to happen. When it does, he goes mental and leaves his box with his body guards, the chandelier hanging in the middle of the seating area infront of the stage is what you have planted the bomb on, once he has left his box, he will come running from the back of the theatre down under this chandelier toward the stage. Just as he is under it, trigger the bomb.

::Just as a note, this is the only mission so far in which I have actually killed more than just the actual mark and finished it with Silent Assassin Rating. When the chandelier drops, it hits his guards? also, I think I finished this with 4 accidental deaths.

Mission 4 - Flatline

Target 1 (Green Dressing Gown) - Wait for him to get on the weights in the gym . Its important not to bump into him while wearing a Therapists uniform as this will trigger him to start going upstairs and wait for you in your office. The times this happened to me, he never returned to the weights. When hes on the weights, approach him and stand behind him facing him, just as he lifts the the weights up and back onto the uprights to finish his workout, an option will appear to drop the weights. Do this, you will knock the weights off and hold them on his neck choking him.

Target 2 (Blue Dressing Gown) - Upstairs of the main building, he resides in the room with guards always outside. Room number is #. Go in through the adjoining room, room #, out the back onto the balcony and into his room through his balcony door. If he is in there just come back and wait for him to leave, then enter the room and tamper with his bottled gas on the stove.

Target 3 (Pink Dressing Gown) - He drinks from a stash in the globe. Get above the glove (through the office of the therapist) and onto the balcony that looks down on the globe, plant the bomb on the wall fitting holding the rope for the rooms light. Trigger when he is getting his booze out.

Mission 6 - A Crows Murder

Kill Angelina Mason - In one of the ally ways that lead to small courtyards behind buildings, there is a piano in the air on a winch. Follow the platform with the winch on around the walls of the buildings and you will see how to get up there to plant the bomb. Angelina will be standing directly under this "at some point". She begins the level here, and slowly moves between all the allyways. She will be back here a short while after the case being delivered cut scene / PIP giving you enough time (if already wearing the bird suit) to nip inside, get the case, and push Mark off the ledge and get back to time the detonation.

Kill Mark Purayah - Once the suitcase is delivered to him, simply grab a bird suit from the guys in the ally way to the side of the building, timing it right so you can pinch the suit of the guy to the right at the top of the ally and dump him in the dumpster and then go inside the building. He is located at the top of some stairs. Again time it so that he has no one in the room with him, and when he walks to the balcony, simply sneak up and push him off the edge. I had to push twice here, and I have still yet to get SA on pro, so I'm unsure if this is the correct way to go about it. I have sedated him and pushed him over and only got professional rating and I see no other way to kill him as he doesnt ever leave the room.

Kill Raymond Kulinsky - The simplest of the hits, just grab a walkie talkie, or listen on the radio as you push the other guy with the case over the balcony for which bar he is in. Always enter each bar from the rear enterance and don't blow your cover. Sneak up to the top floor and he will be in one of the last rooms. Watch him till he moves for the balcony, creep up, and simply shove him off and retreat asap so as not to be seen.

Mission 7 - You better watch out...

Right, first off. I did this on professional, only sedating 1 guard in a black suit, and putting him in a dumpster and that was it. No more kills. Heres how..
From the startm, run right, and wait till the camera is moving fully to the left as you look at it, then run around the righthand side along the railing and through to the guy in the security room. Stand next to the door and wait for him to go get the soda from the machine, duck in sneaking, turn off the lasers with the button on the wall and run out and round to the elevator. Once up there wait for the guards to go into rooms and run through the glass door and outside.
Now here is the tricky part. You have to damage the utility box on the wall and a guard will come out to fix. Its difficult because you need to time this so when he comes out, you can sedate him and drag him around the wall to the dumpster before any of the guards come out of the room and stand infront of the glass doors on there usual patrol. But it is doable. So take his suit, dumpster him and then jump over the railing opposite the dumpster and make your way along the ledge. This will lead you back to the main building. Go up to the first door in this stair well and exit into the kitchen.. Now for the targets..

Kill Chad Bingham - As you enter the kitchen, immediately take the door on your left. In here on the shelves is aphrodisiac. Take it. Goto the bar area. Wait for the waiter to leave a drink on the bar, it may already be there.. Walk to it and it will allow you to press A and put it in the drink. Do that. Go and stand near the pool just outside that has Chad in and some chicks. Eventually, he will recieve the drink from the waiter, drink it, and will get out the pool with a lady. Slowly, keeping your distance, he will go to a bedroom. Wait outside the room till he has finished, and he will go down some stairs. Keep your distance and follow him. When he reaches the bottom and he is stood at the ledge outside, push him over.

Kill Lorne de Havilland - Right. Go back upstairs, goto the kitchen and get a sausage. Then you need to make your way up the curved stairs which say staff only up a level and to the room where the video CCTV equipment is. A guard will move to this room and leave on a patrol. When he has left, creep through the room to the lock pick door and pick it without the guard noticing you that is always in this room. If you creep all the way accross the room, he wont see you. Go up the stairs. At the top is a guard, watch through the key hole for him start walking, follow him round to the first door, then to the second door. This second door leads to the studio where the photographer is taking pictures. NOTE: this second door, you can sit here in creep mode, and when the guard on patrol comes back, he will open the door, conceiling you and carry on going allowing you to then nip out onto the studio floor with no guards seeing you! (use this when making your way out later and the following bit). Now walk left as you exit onto the studio, past the ladder, turn right toward the ladies and photographer until you reach the double door. Go through this door, half way up on the right is a elevator leading to the helipad. The last bit you have just done is how you will get to this elevator without being seen to escape, so its good to get the practise in while in a guard suit so you will know how to exit the level...
Anyway, take the heart door opposite the elevator, to your right is the door to I assume his bedroom, with two glass doors leading outside. If he is not outside, then go back out this room and wait for him to go through the bedroom and outside. Drop the sausage and poison it (Use poison not sedation), open the glass door on the left and throw the sausage outside to the dog by holding the left thumbsitck down and releasing. Move to the right door but dont go outside yet... When the dog keels over, creep out behind Lorne and push him over the edge.

Retrieve the video - When leaving this area to go back and get your suit, nip into the video archive room, just at the end of the hall to the bedroom where you just pushed Lorne over the edge. Stand at the video and as soon as the guards back is turned, nab it.

Escaping - After taking the video, go back down the way you came, to the kitchen, back down the stairs again, over the railing, and shimmy to the dumpster. Change into your suit. Go back over the railing and shimmy back once again and make your way upto the kitchen. Watch out for the drunken santa. Now you are going back upstairs again. It will require you creep about and hide from guards, but again go up the curvered stairs (where you exit the room adjoined to the kitchen) and wait for the guard to leave the CCTV room (just keep opening the door to watch him go) then creep behind the guard standing watching the CCTV monitors and go through the now unlocked door. Repeat what you did when going to kill Lorne, wait for the guard at the top of these stairs to start on his patrol through the keyhole and hide against the wall as I mentioned above so when the guard comes back, he opens the door on you and hides you. Nip out when hes gone past you, and go back to the double doors where the photographer is. Go straight to the elevator, and move to the helipad level. As soon as the lift stops, run out of the elevator turn left, through the door, straight ahead past another guard and through the door, and then run straight to the chooper and hit A to escape ASAP.