I really don't know how that's a mouth in any way, you really should completely make a new one. The eyes ned absolutely tons more details, oh, and I think on the right eye, you should make the outline near the top half gradually go thicker. The hair is very simple and typical, make something special about 'cause I can go and find a crap load of heads with similar hair, (mostly my heads, I must admit lol, I need to practice :l) make it look noticeably different. The colours look pretty common, you should make the skin a gradient (not literally, but just so it changes colour near the middle) supported by some effect on it, maybe grunge or something. I'm only saying that cause I remembered Chris' old angel and demon head, I loved that old stuff.