do you do jibes?
If not, don't ride with 3 footstraps.
Make sure the straps are wide enough to get your foot far in. And don't make it too loose, otherwise you won't have grip.
Maybe you should get the wide straps like NSI or Slingshot, they will give you much more grip.
See this topic with pics:
http://www.kiteforum.com/phpBB/viewtopi ... &forum=1&3