When shooting paintball, any sport, and almost anything else, keep these guidelines in mind:
1. Get low; at or below the subject's eye level.
2. Shoot/crop tight; eliminate dead space (see below)
3. Shoot the fronts of people; backs are generally boring most of the time
For an example, this is your photo edited with guideline number 2. It took longer to resave and upload it than it took to crop, and it's a lot better already.
Consider checking out the photography subforum here
. It has a WDYS this month thread
where you can post photos and request critique, and the PhotoMob thread
that is geared toward paintball photography that is full of people that can help.