Well, some good things are like horse...
some skirmish games, nothing like some competition!
Have some tourneys too, Free throw, 1v1, 2v2, etc...there could be some prizes.
Good warmups can be the dreaded lines....some under the leg/around the neck/around the waist, not dribbling, just circling with hands, its helps alot.
Whatever you do, dont let them pick their teams, a few people who are from the same school or whatever is ok....but we dont want the overpowered friends squad on one group, try to get it split in skills if you can.
Look for some people who can be good leaders, a passer or a person who encourages one another...
Try to get the badness out of ball hogs, alot of kids do it, it is NOT liked by anybody, try just to get them to pass abit more.
Passing drills too.
My 2 Cents