Another Fun Thing To Do:
If a nearby spawn point/zone belongs to the other team, take it. If the enemy is heading for a nearby zone/spawn point with the clear intention of taking it, stop them. If one of your teammates gets the flag, escort him and kill pursuers. If the pursuit kills him, jump in and grab the flag before they can return it. If you're near your home base and an enemy picks up the flag, kill the carrier and return the flag. If you're near the enemy base, hit it with eveything you've got, grab the flag and run for home. If you're at a spawn point with no vehicles available and there's a sniper rifle or binoculars, snipe until you get a vehicle. If you're flying and you see an enemy grab the TOW missile/cluster bomb, hunt them down and kill them. If you're flying and you see a teammate grab the TOW missle, escort them. Use every weapon and every vehicle depending on the situation. Look at the map constantly. Warn your teammates about incoming jeeps/tanks/warhawks/guys with knives. Go to where things need to be done, and go quickly. Don't worry about dying a lot.