Young Guns: Safety on the Range?

Deer seasons just closed in my neck of the swamp, and my club is already putting together work-day schedules, stand adoption sign-ups, and pleas for dues, of course. It's a club with a changing clientele, one with a growing number of younger hunters. That's a huge plus. My 15-year-old son is about tired of hanging out with old men in the woods, and hunting with his buddies is a huge attraction. Now this club is faced with increasing numbers of 14-, 15-, and 16-year-old shooters at our small range. In the past, we've not had a set list of published gun safety rules, but now we're reconsidering that position. We have a small covered shooting house with a pair of benches, a 100-yard range with a bulldozed backstop, and a nearby open field for throwing clay pigeons. In addition to the basics—no loaded guns until you're in a firing position, ear and eye protection and the like—I have a few other ideas for gun safety rules for when younger shooters are at the range. I get very uneasy when folks show up with 3 different firearms at a time. And young shooters with hand-thrown clays makes me nervous. But what might I be missing? Minimum age requirements for shooting without adult supervision? A one-gun rule per person? What specific rules would you insist on in such an environment?