Alright. let's start this off. I'm not really how much of this is "artistic impression" but there are several anatomy issues as well as some composition things here.
First off, you see to have combined a 3/4 view with a front view- ending up with something not quite either.
1. The angle of the neck seems to indicate you wanted the torso in more of a profile view with the head turned towards the viewer. The thing is that it is really akward to have the torso 90* from the angle of the head- it's an unnatural movement and it shows. The neck just sorts of trails off the picture, avoiding the torso problem, but ending up with the guy having a super long neck. To solve this problem, make an indication of the far shoulder like I did at #1 and
#3, indicate another shoulder. You end up with your torso in a more natural position relative to the head.
2. You have a 3/4 view of the head on the outline- the jaw, the ear, and how you attached it to the neck- to the right of #2. At #2 itself however you morphed it into a front view of the jaw, resulting in an off center chin. I decided to change the lines into a 3/4 view- which also means the face would be off, as it is in a front view and slants down to the left in an attempt to align the top of the head with the chin at the bottom.
3. Alright this is fairly minor compared to the others but at #4, the top of the ear should be completely covered, it shouldn't "shine" through the hair.
4. The hair. At #5, I placed a dotted line where the top of the head would be minus the hair. You should try to follow the form of the head as much as possible, else you end up with, say, a crease in the hair up a lot higher than where it should be (circled). At #6, the angled line is the angle of your hairline- the straight line should be the overall impression. While the hairline itself is more of a curve, it is easy to let it go crooked if not watching for it.
5. Composition of the piece. You have a lot of empty space over to the right. (#7). It is dead space, and draws the eye away from what should be the best part of your drawing. You could either crop it away, or put something in it's place.
Not sure what the colours are about though
very vivid.