Howdy. Proportions are looking alright to me. The nose looks crooked, strange, however. The eyes also seem to be shaped perculiarly.
Don't worry too much about which colours you're using at this point, I reckon, just focus on the form.
http://www.anticz.com/drawing1.htmHere's a tutorial that talks a bit about shading a form, check it out, hopefully you'll be able to see how the form in your piece is broken by its shading.