I teach mainly young kids. I have to say it took me about a years experience to really understand how best to control the kids in my own style. I don't use a lot of discipline and rewards, but I try to plan the class to help keep the kids attention.
I wrote on my blog my top ten teaching tips for teaching young kids, check that out here:
10 Teaching Kids Tips « Dream English’s Weblog
Without going into a long answer, I would say be as organized, simple and consistent as possible with your classes. The students will become used to your routine and you as you get to know each other. Hope this helps a bit, there are many more ideas on my other site
Dream English Kids Songs, free mp3 song downloads,flashcards and lesson ideas,let's sing!