Roll the bones

Taken alone, which looks more like a tree:  the trunk and branches, or the leaves?  The same holds true of the figure.  Without a solid understanding of the skeleton, the figure won't work right.  This is especially apparent in portraiture -- a good drawing of the face is also a good drawing of the skull beneath it. 

I don't have any portraits, or even skull drawings, handy.  But I do have a hand.