@ Ivvy - I try to help artists when I can. I can't really spot small mistakes, since I'm not an artist myself. But I've seen art and the critism other people have given on it, so I have a vague idea on what to suggest.

@ Wingless - Your lines are really blurry. I would suggest that you try to make them straight and neater so that its more appealing to look at.
And you should work on your anatomy, also. Take the following image for example.
http://theopression.smackjeeves.com/...49322/symbols/
Work a little on the hand. Hands are hell for everyone, I know, but you gotta pratice. Also, the way her upper body and hips connect to her torso is really unnatural. Also, if her ears were really where you put them, they would be attacked to her cheek. They should be a little farther back. Probably higher, too. They should line up with the eyes. And would people with wings sleep on their back? It seems a little painful, but I'm nto really sure about this one. It just seems like they'd sleep on their side or tummy.