First off I really like her clothing.
I think that there's something wrong with her arm there, like she hasn't got any triceps and maybe that her elbow seems a bit misplaced, you should look over that again.
Concerning her hand... If you look at your own hand, in a open palm position, you'll most likely see that your thumb will end about where the others begin. And the little bend where the thumb crops out from the hand is much higher than it is on your girl. I hope that helps.
"A pat on the back is only a few inches away from a kick in the ass."