I think your youth will have SOME people not wanting to use you, but will be even an asset for others. Some teens, or 'tweens will LOVE having a teacher they can really relate to.
First and truly FOREMOST: GET INSURANCE!!!!! nuff said.
Second, remember that being a good rider or horse person is only half of the equation. Being a good TEACHER is almost more important. That means being a good communicator. Being able to teach something that must actually be learned purely by personal, physcical experience is tough. You cannot step into that person's body and feel what they feel. You cannot 'give' them the feeling you have in your own body. You have to learn how to describe in words, a thing that is really a 'feeling'. That can be challenging.
I would suggest that you watch as many other people instructing riding as you can, both in person, and on the internet. Observe how the explain things, any tricks or games they use successfully. Learn how to give knowlege out in digestable amounts (not the 'trying to drink a sip from a fire hose'), how to order things in logical steps, etc. And, how to see things from their point of view.
Teaching well has a lot to do with being able to see where the other person is NOT seeing. To see their blindspots, and become able to rephrase things so that they CAN understand. Communication, communication, communication.