Dark Sector

Easy breezy, since its the begining of the game, you really can't lose.
Check the vid for more info.

You'll start the first mission without the glaive or any of the powers, so try for headshots with the pistol until you pick up an assault rifle from the guards. The final boss fight for this mission might also be frustrating to some, especially on brutal difficulty so make sure you kill all the guards before you grab the RPG. If you hide behind the crates, the guards will tend to group up by the truck, at which point you can use your grenades liberally, as you'll lose them anyway at the start of the second chapter. Grab rockets from the crate first then grab the RPG because I'm pretty sure picking it up triggers the helicopter to attack. Stay behind one of the large metal crates and lock on to the chopper using the cornering technique before firing your rockets and this fight shouldn't be too difficult.

(The video belongs to BonersGames)
(FYI i used http://www.xbox360achievements.org/game/dark-sector/guide/
credit belongs to wickeddark)