Conceal yourself from enemies. They can't shoot you if they can't see you. Indoors, wear dark, blendable clothes, nothing white (stands out under black light) or interactive with black light (such as certain hair gels or face paint). Outdoors, camouflage works well.
Use others as shields. When leaving a home base, move with the group. Don't be first or last to enter the field of play.
Keep moving. Continuous, random movement keeps your body sensors in motion, making them harder to hit. It also puts you in firing range of your enemies so you can score points.
Be aggressive. You win more points for making a tag than you lose points for being tagged.