The best tip I can give you for these is to keep very straight. Like somebody has a hold of your head and is lifting you by it. That and watch the centre line as you put it on your head, to get it in a good position on your head. In the video I try (badly) to go from a steve into the head spin and then back into a steve. This is my current 'fun and stupid' thing.
http://tutorials.firestaff.net/tutorials/tutorial-videos/wmv/bodyrolls/Headspins.wmv (Right click, save target as... )
Streaming Flash Video: