Naw, I know what this needs.
The 3/4 head, if it is, doesn't look much like one. You don't make a 3/4 head by drawing the frontal face and pushing it (or the nose) to the side a bit. Constructing the head and facial features out of those old 3-D shapes (spheres, cubes, cones, cylinders) makes it easier to add real tilts and angles like this, and shade it too. While I pretty much winged it here I might do a breakdown of this pretty soon.
The palette came about by tweaking, seeing if one color is too similar to another to get rid of it, combining 1 color with another from one of 2 different "ramps", those kinds of things. No straight value ramps and, ErekT's point, no greys.
Arm holding pizza seems uncomfortable, and does not provide a very good silhouette for the pose. There's a thing called negative space, the spaces between limbs and details that makes a pose more readable. Try lifting that arm up a bit, maybe even give some space between the left arm and jacket. (
EDIT: Lifted the arm up.) Also, simplified pizza drippings.
Ashbad, you have a good point about contrast but your own palette chosen for the skin particularly, is a bit backwards. (With no other influences and non-diffused lightsource) the middle tone would be red and saturated, not the core shadow. The opposite gives the impression of colors selected randomly. Also, speculars are never directly on the side of a round object unless the lightsource is starting to go behind the object, which the shadow on all versions of this piece do not suggest. This applies for the original image as well--note the saturated skin tones (except around the chin) and location of the speculars in the edit.
Hope this helps, wanna see where this goes.
