Wear a watch, don't get too hammered the night before, drink plenty of water, if you can have a good walk around the game area the day before it helps a great deal in knowing where bases and tracks are. Don't get too hung up on winning or loosing just play for the fun of it.
Get an understanding of how the game is being run:
Are there points for eliminations (eg are players counted as they go through respawn, are paper arm bands in use being ripped off when eliminated and replaced on respawn)
Are objectives to be held as long as possible, or at key time points
Eg should you just capture land and buildings etc and hold them as long as possible, or could you not worry about them for the majority of the day but make a rush to capture just in time then give it up and move on for the next objective
Are there other tasks that could be done, eg search and gather objects
Are there any unusual rules to look out for - eg air strikes, and how they function - if you see a circle of Marshall's around you with umbrellas then it may not be about to rain
More importantly - how do you like to play? Make yourself known to the leader and offer out your playing style. Leaders are always in need of someone to take on a task, or even to head off in a direction picking up odd players and setting up a new front
Don't waste paint trying to hit targets in the far distance, you won't. Always be thinking about what's around you and how you can move forward. Work with those around you and if they're far to lazy to get off their fat arses then try to rally them up and bust some moves.
From having gone to a couple, it's simple. Sprint like a mad thing down the field, then slow down, clutching your side, and advance "tactically". As soon as you see one or two others and paint lands near your, crouch behind cover, and shoot at the vague shapes of the opposition in the distance until you run out of air or paint. Then, return to base and repeat...