On Halo I love to equip the handgun and pistol-whip the other players to death, and I'm actually pretty good at playing it that way. Otherwise and in most other fps games I just blast everyone with any smg or shotgun.
Im not one for FPS games but when my friends drag me round to an Internet gaming cafe I'm one of those clueless bastards who sits at the top of a bridge with a sniper rifle and shoots people as they walk under.
I like running up to the enemy and dealing with them face-to-face, harr. Blast them away with some bazooka or shotgun, whatever kills them in one blow. Probably not the best strategy, but it's kinda fun.