Leaves always turn a lot. Look for reference videos maybe?
I find this one's good, but it lacks the wind:
http://www.youtube.com/watch?v=-NYYWp7Pa7s

another one where they turn and twist a lot:
http://www.youtube.com/watch?v=DLr1oWjIC44

I think if wind blows, they often fly back up a little (while being blown away) before tilting to make a looping and then come down at a steeper angle.