By the time they were old enough to hunt (12) both my boys knew what they needed to know about treestand safety. I figured if they were old enough to be responsible enough to take a life, ethically, then they should be able to handle the safety responsibilities that go along with that. First comes the skills, then the "gravy" of being able to hunt. 12 year olds are much better at climbing trees than I was.....it was just a matter of learning correct techniques.
Having said that, stands were always hung by myself, and everything in place, and getting in and out was fully supervised by myself....and I also had a stand clearly in view and close proximity, so that if any problem arose, he could get my attention at a glance.
We did'nt use ladder stands then, and now that we do, I would highly recommend that option. And the double ladders (2 seaters) are a great option.
Hunting off the ground is also a great way.
Another great way to keep kids interested and seeing game, especially the younger ones, is to conduct small one-man pushes with a friend to help. We liked to do these during mid-day, and not in the same areas we did our stand hunting. It is very important to make up ground rules for possible shooting with first-time hunters....and it's a great way for some action at close quarters with kids who are along for "the fun" and experience. Pushes have to be carefully planned and executed to be of any use for bowhunting, of course, and that needs to be kept in mind with young shooters, and even with yourself setting the example for young eyewitnesses.
My son Kory, at 12, killed his first whitetail doe from a one-man push, a perfect double lung shot with his recurve, and I was there with him to witness it. Great memories!