To be nice to dblref, I will refrain from saying what I really wanted to say in response to your query. Then again, he could probably respond about what it takes to coach AAU
To ref AAU, all you really need to do is be a member of an association that has as contract with one of the clubs that run tournaments, and show an interst. It is not so easy to find refs that want to do younger age groups, especially for the girls.
My club, the Vogues, and the Cardinal are the prime tournament host clubs in our area. Fencor in Philadelphia holds quite a few. Most clubs host at least one ournament, some go 3-4 per spring, and some very few clubs are out there all the time (Kenny Farmer in Mt Vernon is running nearly every weekend!)
http://www.usjn.com lists many of the girls AAU tournaments on the East Coast under their EGBA Master List page, which also includes a smattering of mid-west, south, and western tourneys. Not sure where the best source of boys info is.