I recently posted a link to Evelyn Matlin's post "A Few Tips For New Magicians." Greg Frewin Theatre also has a similar post up "The Greg Frewin Theatre's magic hints and tips for your children."
From the Greg Frewin Theatre blog:
Magic is fascinating and can captivate audiences of all ages. We've discussed some of the most popular types of magic before, but where do you start when your child has started showing an interest in magic? Whether your child will be performing in front of you or just a few stuffed animals, they’ll need to know a few tips to help them get started.