Might want to look more into basic anatomy, and keep the reference in hand. Do you have the reference right next to you or easy/quick to access while you work? Cause you should. On anatomy, since it's just the head from a side view, it's nothing too big to study, and in fact i think that was the first head angle i studied in art class. Hopefully
this video can help you a bit as well.
Here is a "Demon Days" picture from wikipedia, in case it might be helpful. Look out not only for the style he uses for anatomy, but for light/value and colors as well.