ok, i have not been playing long, but i am fortunate enough to have joined an experienced team( one of the only bad things about them is that they sandbag. they should be in novice/amateur but we are going into the rookie division in the 03 mardi gras, of coarse that is mainly because of the price increase per division.)
one of the most important things is to comunicate. back players should be screaming their heads off the whole entire time that they are in the game. they should be telling the front/mid and even the other backs where the other team is. they should have a bunker that they are primarily shooting at. for instance: i go the back right corner right off the break, since we crossfire, my main objective is to make sure the other teams back player in A-1 (the back right bunker for them, the bunker all the way on the other side of the field on the right corner for our team) can't shoot at any off my team mates. this takes ALOT of paint. i dont have to worry about the other people on the other team because the rest of my team is crossfiring as well. the way we set up everything makes it where everyone covers everyone else's back.
stay in good physical condition. learn how to snapshoot properly
learn how to dominate the other team (ie: make it where they cant snapshoot or pop out or anything like that without getting shot so they sit behind their bunker)
learn how to run fast.
learn how to keep a cool head during a game. the last thing you need when the rest of your team is gone and its you against 5 other guys is to freak out and start making stupid moves.
and dont skimp on the equipment. sure, the marker doesnt make the players, but you cant play competition paintball with sucky equipment.
listen to and learn from more experienced players.
dont get mad when you loose. think about what you did wrong and dont so it again
dont cheat. cheating is the worst possible thing that you can do and it will be remembered by everyone who saw/ heard about it for a long, long time
have fun
i hope that some of this stuff helped
later