Snap shooting practice, start with several stationary targets and pick spots to shoot each target, have your player start at the dead box, and run to the first spot. They snap out taking one shot on the target then checking in until they hit the target 3 times. Then run to the next target, rinse and repeat for each target/player.
Snap shooting on a live target. Have two players snap battle, they may post as long as they wish, but once they fire a shot they must check back into the bunker.
Running and gunning: Spilt your group into two teams 2v2 or 3 v 3 (more if you can manage it) you will also need ~ 4 players to be refs to enforce the drill. Have them play games, any time a player doesn't have their gun up shooting or on a target when moving, call them out. They should learn to keep their gun up when moving or keep shooting when on the move.
Target courses: setup multple targets on a field, have them lane, snap and run and gun to shoot targets. Make them shoot from kneeling, standing, laying down. Players should be running to each station if it is not a running/shooting target. If you need to slow it down for people to learn how to move with their marker do so.
Pod drill: This is to build player confidence and communication.
Take 3-5 players as runners and 1-2 shooters. Place shooters and runners on opposite ends of the field. The shooters should be outfitted as though they were playing 3-5 man depending on the # of runners.
Place pods at random bunkers across the field up to the 40 from the shooters side. The pods should be accessible to the runners.
The runners must "collect" or throw every pod off the field. The shooters should eliminate the runners. Runners do not carry markers (or if you want them to carry them to get sliding running practice with them, do it without hoppers/barrels). The shooters must stay behind their 20 and play in bunkers as if they were being actively shot at or in a game. If they don't have another player standing on the back line of the runners side that is allowed to shoot the players on the shooter side if they continuously leave the bunker when not moving to another shooting position.
Players on the runners team need to keep in constant contact to know when they can move and when they need to draw fire. Shooters need to keep in communication to ensure that they aren't getting run on.
The runners win when they either can "bunker" a shooter by running past the 20 of the shooters side, or when all pods have been "eliminated"
This also helps with players who are affraid to move when being shot at.
These are a few that should help you get started, I'd also suggest checking out Dynasty dysected or One with the gun for more ideas.