Too be honest, this is pretty potent for a first. Alot better then my first.
I opened it on a gray bg and it seemed kinda distorted, white dots everywhere. Did you save it as a JPG at first or something?
Don't go with the black outlines. You should nearly never use pure black. Just use a darker colour.
You should study lightsources a bit. Some stuff like the face look pretty correct, but the neck shadow looks wrong. It should round towards the middle of the neck, not to the sides. It looks hole now.
You should shade the hat, and study spheric shading. It's unlogical that the light is to the edge of the hat.
Here's an example of how to shade a sphere:
The underside is slightly lighter to the edge as you can see, this is cuz the light bounces of the floor back onto the underside of the sphere.
Off course the bouncing does weaken the lightbeam. Lightbeams bounce at the same edge as they hit the floor. So if they hit with an edge of 40, they bounce the other way with an edge of 40.
