Do you know how to strafe? Something that always worked for me when learning a new multi-player FPS to calculate how long I would live before I was killed. If it wasn't very long I would find any gun and just start shooting all over the place. By the time I ran out of ammo I would statistically be dead anyway. Weapons that bounce off of walls or have a delayed explosion are preferred for this method because killing another player by chance in a FPS is not hard to do. Rocket Launchers are also fun, just remember to try not to blow yourself up, but if it comes down to another player shooting you at close range or you killing both of you with a rocket, kill both of you with the rocket everytime. Don't forget, other players must recollect their weapons when you kill them, so kill them at any cost. After following this method for a while, you will become more selective with you shots and better at saving yourself, thus a better player.
Remember, don't just take the good shot, take all the shots.
NoBonus
pain in the butt to play FPS with