If you're a newbie to paintball, here are some tips about playing that might help you do better on the field... know before you go! 
1.  Don't play in paintball games that are beyond your skill level.  If you're just getting started, play with a crew that have played less than 10 times and you will have much more fun.  Some guys get cocky real fast and think they can hang with black belt paintballers (guys who've been playing for years), step out into the field only to have their jerseys re-colored with paintballs.  Paintball players may get over confident for a number of reasons.... They may be longtime hunters with their dads and think this type of experience would translate well onto the paintball field.  Some of them might have even made some killer shots at the shooting range and think they're an expert shot.  And then there's the jocks who have always been the best player on the field no matter what sport it was.  No matter what, if you're on the wrong paintball field, you'll know it very soon.... it won't be long until you're annihilated in a barrage of paintballs.  Keep your confidence up by playing in paintball games that suit your skill level, and try to move up one level at a time.  Great skills are developed by practicing for a long time.
2.  Before the game starts, make sure you turn off watch alarms, beepers, and cell phones.  Take the barrel plug out of the gun just before the ref shouts, "Game on!". 
3.  This seems ridiculous, but make a mental checklist of team colors so that you don't eliminate your own teammate in a friendly fire accident.