well, depends on the game. In Call of duty im a bit of a krazy beetch, the idiot who assaults the enemy MG nest with a fucking bolt action rifle. Thing about being good a at the game, though, Is I dont try fire at the guy, I just chuck in a freaking grenade. if hes smart he will un-deploy his gun and leg it, but this is about as good as killing him - it allows our team to advance and hopefully fill his back with enough holes for you to mistake him for a red type of swiss cheese. One of my favourite tactics in CoD5 is to run right up to a tank, so It cant shoot me, then I chuck grenades all round it til it blows up, or the driver gets out so I can fill him with lead.
In, say, TF2, again, id be the guy to try take out key positions even at the loss of my life. Ergo: I like teh spy. For example the enemy have a crackshot sniper who can take out everything he sees in a second? Well, Id sneak in and stuff a knife in the back of his head, see how he likes that. Or maybe my, what id call a signature move, as ive never seen it pulled off by anyone but me as you need to be REALLY fast. Go up right behind the engineer, knife him, then Instantly change to your sapper and sap the sentry right infront of him before it can even lock on to you. Result - Sentry down, engineer down, my team gets to move up. And then I pull out my revolver and help them with the attack. In many capture the flag games, as well as being a crazy beeyatch who does crazy, risky stuff like the two scenarios mentioned above,
I often just grab an engineer, build as sentry at a key position and watch the fireworks as scout after scout are mowed down.
In COD, I just do the quicker and simpler version - plant two fucking mines beside the flag...and watch the fireworks once again.
In battlefield games I provide medic support and get into the bomber planes to, once again, take out key positions.
But all in all I rely on brains more than brawn during team based games. Charging the enemy head on with an assault rifle isnt always my thing. Sometimes do it, but not often.