Wallace: Haphazardly shading the borders of his features does not a good CG make. The hair is pitifully half-assed, and his hand looks like a flipper. Accentuate it more to make t look slightly more human, and give him a thumb.
Steven: There's almost no shading on this one, save for the face, and again, with the half-assed hair. proportions are decent enought to get by, though. You just needs shading tutorials, and make facial features more defined. An example of good definintion in a finished CG:
Here
And example of well-defined hair:
Here.
What program do you use? If it's Photoshop, I can tell you how to get results like those.