Terminator Salvation

There's not a great deal I can offer you in terms of how to get this achievement, it's all in the description, complete the first mission of the game on any difficulty, however you may find these videos of the first level handy, it'll help you get your bearings on any part you might be stuck on and give you an idea of what to expect!

The video walkthrough is being played on the hard difficulty, while this may not be needed for this particular achievement, there is an achievement which does require you to complete the entire game on hard mode, the game isn't that difficult and you shouldn't have too much trouble with it if you do decide to playthrough on hard, just follow the videos so you know what enemies to expect and when to expect them.

* ^{Credit to Madzarzour for the videos}