The best promotion of cadeting is simply being an active club. The point is to get creative so people and the media will take notice. It never hurts to call local media and let them know what's happening. Don't be discouraged if they don't take any interest in covering your event. Just keep making calls and eventually they will feel obligated to check it out.
Prayer is powerful.
Pray that your club can be a tool in God's hands, a light in the world. Hopefully, your activities as a Cadet club will cause other churches to seek you out. They will wonder if cadeting is a good way for them to reach boys for Christ. The Cadet organization has a few tools to assist you in helping them discover the answer. You can also direct them to this Cadet WEB-site which they can browse at their leisure.