Starting to shape up pretty nicely, don't worry too much about the silhouette, it'll shape up when you begin adding muscles. Also I think it'd be in your best interest to make the figure from three different angles (front, side and back that is), will give you a better feel for where everything is.
As for the head, I feel it's fine as it is proportion-wise, although you should make it narrower (you could also make it shorter if you want, but it's not necessary).
On a side note; the head is a completely different beast in terms of anatomy, generally even if you study it (both skull and the muscles that overlay it I mean) it won't give you a full understanding of the human face, in order to achieve that you need to practice/draw a lot of human faces (even with the body you need to do that, to a lesser extent though I think).
I feel that the head of the femur is sticking out too much. It should almost line up with the hip bone vertically (as with the rib cage), just barely sticking out, like 1 pixel horizontally I'd say (look at my edit to see what I mean).
I'm under the impression that you're making a male skeleton, if not the shape of bones has a slight difference, or rather the proportions have a slight difference (bigger hips, smaller shoulders for an instance), so which one is it?
The hands are a problem, as with the forearm, work a bit on that.