I agree with Drew. Get Brian Flora's tapes right away - for someone who wants to get into the after-school teaching of magic, these tapes will help you a bunch.
Flora's stuff is expensive (BTW, he passed away about a month ago, but his wife Jan is still operating the business), but worth it. He covers it all: what to do during the class, what to charge, material fees, classroom management, etc.
I've been teaching magic classes for many years, and Brian's tapes Drastically changed my approach. My classes are much better after following Brian's formala for success.
He also sells a second video tape by Dave Risley that covers teaching magic in daycare centers. I have that tape too, and it's excellent if you're into that market.