Concodrance Officer 
Collect all Trophies.
Self-Explanatory.
Dead on Arrival 
Complete Chapter 1 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.
Lab Rat 
Complete Chapter 2 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.
All Systems Go 
Complete Chapter 3 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.
Cannon Fodder 
Complete Chapter 4 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.
True Believer 
Complete Chapter 5 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.

Greenhouse Effect 
Complete Chapter 6 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.

S.O.S. 
Complete Chapter 7 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.

Strange Transmissions 
Complete Chapter 8 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.

Wreckage 
Complete Chapter 9 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.

Keeper of the Faith 
Complete Chapter 10 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the tram at the end.

Betrayed 
Complete Chapter 11 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the ship at the end.

Exodus 
Complete Chapter 12 on any difficulty setting.
This is pretty straightforward. You unlock this as you enter the ship at the end.

Survivor 
Complete the game on any difficulty setting.
This is pretty straightforward. You unlock this along with Exodus on Chapter 12.

Epic Tier 3 Engineer 
Complete the game on the hardest difficulty setting.
Complete the game on the impossible difficulty. Impossible difficulty unlocks when you beat the game on any difficulty. This is by far the hardest trophy to attain. Conserve ammo and aim for limbs.

One Gun 
Beat the game using only the Plasma Cutter.
I recommend you to do this on your first playthrough. The Plasma Cutter is the first weapon you get and is not underpowered in anyway after it is upgraded. The other weapons can be purchased; just don't fire any of them.
One Gun can be gotten on a 2nd play through. Same rules apply of course for that play through. Credit:
Con818 for this tip.

Pack Rat 
Store 25 items in the Safe.
This is very easy and can be completed at pretty much any stage of the game. To complete it, simply enter the Store, click on an item, and then choose move. You can move every item to your Safe then move it back to your Inventory if you are impatient.
Story Teller 
Collect 75 Logs.
Although it may not seem like it, this is very easy if you just make sure to pick up everything and you search everything. A step-by-step guide is not necessary. Remember blue lights on cabinets will open, and green chests can be broken. I got this near the beginning of Chapter 5.
Legend Teller 
Collect 150 Logs.
Once again, not that hard. 150 is not all of them, and a guide isn't necessary for observant or thorough players. I got this about midway through Chapter 11. If you skip a lot of areas or are extremely unobservant, I won't guarantee you'll get this without a guide.
Full Arsenal 
Own every Weapon in the game.
Another easy one. Simply purchase all the weapons from the store after finding the Schematics for them. Also, make sure to return the Schematics to the store, otherwise they're useless. Schematics appear as dark blue, shiny objects and are relatively rare, so make sure you at least get all the weapons. There are a total of 7 weapons. I got this at the end of Chapter 4.
Z-Baller 
Complete Level 6 in Zero-G Basketball.
This is also a mini-game and is easily spotted on Chapter 10. In order to win, you have to jump to each of the lit up platforms to generate a score multiplier, use Kinesis to grab the ball, and shoot it in the goal at the end of the room. For more detailed instructions, there is a Log in the game to help you.
An easy way is to stand on the front platform, shoot the ball, catch it as soon as it leaves the holes, shoot back in, finish game, exit the room, repeat. Credit to
Con818 for this tip.
Merchant 
Collect 8 Schematics.
This is very easy because 8 is only about half the number of Schematics there are. Once again, Schematics appear as dark blue, shiny objects. This is unlocked at the very, very beginning of Chapter 4 if you've gotten all of them so far.
Armstrong 
Shoot 50 objects using Kinesis.
Very easy. You can get this as soon as you are given Kinesis by just randomly grabbing and firing objects. After you grab something, make sure to press the right trigger to fire. It doesn't even have to be fired at an enemy, just fired in any general direction.
Marksman 
Dismember 20 Limbs.
This really needs no explanation, as this will probably be the first achievement you unlock. Remember that dismembered limbs are the name of the game in Dead Space. Always aim for the arms or legs.
Surgeon 
Dismember 500 Limbs.
You'll get this just by playing the game as long as you're playing the game correctly.
Butcher 
Dismember 1000 Limbs.
I got this on the very last part of Chapter 12 with only two or three enemies to spare. If you don't get it in time, don't worry. Just keep playing, and it'll unlock before you know it and yes, it is cumulative through multiple playthroughs.
Freeze 
Use Stasis on 50 enemies.
This is fairly easy, just use it every now and then, especially around the recharging stations. It'll unlock pretty soon. I got mine on Chapter 5.
Crackshot 
Achieve a Perfect Score in the Shooting Gallery.
This is a mini-game and is easily spotted on Chapter 9. You have to shoot every red target and miss every blue target in the Shooting Gallery. You just have to hit the targets; head shots are not necessary. There are 6 levels you have to complete with perfect scores to get trophy.
Air Alert 
Zero-G Jump over 100 times.
If you're planning on getting the Z-Baller achievement, don't even bother spamming the jumps to get it early. There is at least one Zero-G area on every level. I got this on Chapter 10 in the Zero-G Basketball Court.
Brawler 
Kill at least 30 enemies with a melee attack.
I found this one to be a lot harder than it sounds. Its pretty difficult to just beat-down any of the enemies, but there is a way around it. Just shoot them with Stasis first, then punch or stomp until they split to pieces.