Nancy MacIntyre’s has a legacy of successful kids apps - and has some great notes over at gamasutra.com.
Not to break it down to an absolute minimum but Nancy has five highlights that add to the success:
1. Make Great Apps.
2. Get Apple on Board.
3. Reach Out to Parents.
4. Garner Awards.
5. Plan Regular Updates.
6. Build a Strong App Store Presence.
That’s really the bare bones - go read the piece at gamasutra for a lot more.
MacIntyre highlights the upcoming changes on both Google Play for kids education and on iTunes with their planned iOS 7 Kids Games stores as real potential markets for highlight and getting new apps and games found easier.