Generally, the idea is to get some good 1 v 1 fights going. If you see two people engaged, let them fight it out to the death. Then give the survivor a minute to get his bearings, build a bit of E and then attack him unmercifully 1 v 1 until someone loses.
5k above the local terrain is considered as max alt until engaging and diving from 10K passing through 5k and then calling "fight's on" is considered poor form.

Now, it doesn't always work like this. Sometimes the milkmaids already in MW get annoyed and
try to fight. That usually results in a milkmaid slaughter by all hands. That can be fun too. Hajo can tell you about this.
Also, you have to expect griefers that will hear about this and come just to cherry pick such goings on.
The important thing is to get a bunch of people together that like fighter air combat. Seems like things just naturally take care of themselves after that.