At the moment it's almost pillow-shaded, especially the fingers, try to picture the forms in your mind and see where the light would and wouldn't hit. If you can't picture the forms in your mind, or even if you can, plop your hand down and use it for a reference, close the blinds and point a desk lamp down at it or something, and you'll be able to improve it even more.
The thumb looks like it's in a position thumbs can't be in. Is that light spot on it supposed to be the nail? If so, it's too big.
The heavy dithering you've got all over is doing nothing for it.
As Xion said, you're using too many colors, the second lightest and third darkest could probably both go without much loss of detail. I'd also do a bit of hue variation in the skin colors, maybe make the highlights a greenish yellow and the shadows puple?
The shading on the head(?) isn't too bad, and I like the knuckle wrinkles on the middle finger.
Fangs might be cool.
Wait, fangs are always cool!

Edit: Also, this could be a buttload of fun to animate, just think of all the wacky movements and attacks it could have!