Yeah, after ultimaodin's post I started looking at my own hand and realized right away that the nails should not be visible. I also definitely agree about the shading transition between the fingers- I don't know why I didn't follow the reference on that one.

Thanks to you both for your constructive comments!

Good point that you didn't copy the ref!

But I think you should better use realistic refs, and even better actual hands (yours).

The actual aggressive gesture would have the fingers much more clenched, and you wouldn't see the nails (as in the ref).

There is a weird shading transition between the 2 leftmost fingers.

 No, I just used that one as a reference, and then my imagination. Here's an edit on the palm area: img13.imageshack.us/img13/3977/fistbump.gif

Think that's a step in the right or the wrong direction?

It's very stylish but since hands are the only piece of anatomy I'm any decent at the shading is entirely warped. I understand that you were trying to create a resemblance to the ref but your also trying to use more natural and relistic lines so shading should also head in a similar direction. The left side is beyond confusing There typically isn't such a dip in the centre of the hand with the pose it's currently in. The light at bottom of the palm shouldn't be entirely cut off from each other by the black. Did you use any other refs or just your imagination?

A very nice and stylish piece just looks a little deformed that's all.

Your AA is good by my standards. ;-)