Turret Expert 5
Shoot down 30 Zylon Fighters in Turret Mode. Hard to miss. 'Turret Mode' is your ship's third form. After equipping an android co-pilot after the third tutorial mission, you'll be able to transform by pressing LB. Get to Turret Mode by pressing LB twice. It's a very slow moving mode but has excellent rapid fire. Get 30 kills with it but do it across several levels so that you don't miss the Model
Destroy a Zylon Frigate without destroying any of its weapons. You'll encounter many Frigates in the game and many of them will be main objectives for certain levels. Take one down by shooting the green 'generators' on them - these are cylinders that pop in and out of the Frigate. Generators turn yellow, orange and then red as you damage them. Shoot these, avoid guns and you'll take the frigate down. The achievement will pop right away.
Destroy a Zylon Cruiser without destroying any of its weapons. These are the bigger ships that'll turn up around mission 4A. They have more generators to shoot and more guns (to not shoot) but are easily dealt with. Occasionally they'll self-EMP (they'll flash blue and their generators won't pop out) but they'll return to normal soon enough.
Star Raider! 50
Complete the game. Not missable. Simply complete mission 10A and it'll pop at the end of it. Mission 10A is the bitch of the bunch though. You've still got infinite respawns but there is a time limit at the end. The main objective here is to shoot the generators to open the entrance. Follow your white indicator arrow to the hole in the ground and go in. This bit is signposted really badly but here's what to do.
Enter hole and go through tunnel, go through either of the next two tunnels (shoot the spinny things, they'll just get in your way later), go through either of the next two tunnels (same again), go through the single tunnel (you'll see bright orange at one end).
Follow the lava to another entrance, go through that tunnel, look for the next entrance on the other side of this area, go through that to get to the 'Core'.
You'll get a checkpoint here. Destroy any gun emplacements and enemies, they'll just get in the way. Shoot the 6 yellow target things (the main objective). At this point I'd consider crashing the ship so that you get full health. Enter the orange cube of light (to 'drop the bomb').
At this point you have three minutes to get back to the surface. It's not much time given that enemies will be shooting you and you've got to navigate these dark tunnels. If you can make it back the way you came, the whole place explodes and it's game over (in a good way). Get lost in the tunnels and the whole place explodes and it's game over (in a bad way).
Arms Dealer 20
Buy all the Weapon Upgrades and Android Co-Pilots in the game. VERY MISSABLE. You can't replay missions at the end so it's important that you raise all the funds you can from each level. Nearly every level has little gold asteroid things (worth 50 credits each) and also enemies that aren't main objectives. Shoot any Frigates, Fighters and Cruisers that you can. Save the main objectives until the end.
Level 7A is great because it has blue fuel cell things (a main objective) that are worth 300 credits each. There are loads of them on this level. Get them all for loads of cash.
If you're having problems buying anything, it's because the game was developed by idiots. At the end of a mission, go to the galaxy map screen and press Y to return to your main base. This is where you can buy weapons. Buy everything but note that some of the heavy weapons are hidden at the top of their respective lists and not always the bottom, so make sure you scroll through the whole of each list.
The final upgrade is the android 'Brain'. You rescue him on level 9A from the Base Star. The achv pops as soon as you do (if you've bought everything else). I had all the money I needed by the end of mission 7C.
Score a Zylon Fighter kill in each Transformation in every Story Mission. VERY MISSABLE.
After the three tutorial missions, you'll be instructed to buy an android co-pilot. Doing this will allow you to transform your ship between three modes by pressing LB. On each story mission (these are the missions that have an A after the number: 1A, 2A and so on) make sure to take down Zylon Fighters with kills from each mode. It doesn't matter what weapon type you use (left or right trigger), just get the kills.
At the end of the mission, you'll get a summary screen that gives the number of kills in each mode - it'll look like 3/4/2 or whatever. Make sure you get a number in each stat. You can press B here to go back into a level, sometimes there will be Fighters there to kill.
The other mission types don't seem to count (the Bs and Cs). This achv popped for me during mission 10A (I got one kill of each type right at the start and it popped there and then) but I still had mission 10C left to play.
(note: this has to be done in one playthrough - thanks BudzMcGee
for the confirmation)