Marksmanship Qualification Program or any kind of pin or achievement patch works great. Crown Awards will make anything you want for a very reasonable price. Try and end some of your practices with games, Annie Oakleys, Buddy, etc, my kids just love the games.
One thing we started this year was to rank all of our shooter based on skill level and match them up, highest with lowest, 2nd highest with 2nd lowest, and so on. Then we shot practice with the best shooters shooting and the least experience shooters watching from the 27 yard line. When done, we asked the ones watching to say something positive about the shooters that they just watched. With the coaches there we talked about the observation and when we were done we flipped and the least experienced shot with the more experienced watching. Ended up as a great teaching opportunity.
One thing I do caution is to make sure they do have time to bond as a team. My kids shot with a sporting clay team this year and there was no time for the kids to bond....sometimes the downtime in trap can be a blessing.
Roger