Be sure to keep from going past about 90 degrees in your knees too. It puts a lot more stress on the joint than necessary. Of course part of that is coming down in the right position too. If you're already leaning back too much when you touch the ground it's kinda hard...

Hey all who are struggling with their roll.

I just developed this video. It should address all the major problems mentioned on this topic.

http://www.youtube.com/watch?v=y6I1J0zmE7U