Here, we shade in the eye, the nose, the teeth and the lips. For the eye, you can have a normal eye, or whatever you want but I chose to have pure black eyes. As for the nose, make the area below the highlight darker than the part above. You can't really see that I did it with the scan but it makes it look more three dimensional. With the lips, shade where the top of the curve is for the upper lip and shade most of the bottom lip. I like to add a little highlight in the bottom one as you can see in the pic. For the teeth, I know these are really unrealistic but they look pretty cool. Remember to draw the upper teeth first and then draw the lower teeth below them.