Well, to keep balance, try to use all of your body parts. Lowering or raising your arms could help a little, but don't make it look spastastic. Your glutes can help you greatly in balance. Also, don't forget about your lumbar, it's a little uneasy to get used to using, but you'll find it useful when staying on your feet.

Now, here's a little test with my new "knee" type of spins. This wasn't meant for realism at all, only style.