Thanks, guys. I appreciate the encouraging words. Brynn, I am hardly an expert at this myself, and am still figuring it out as I go. I'll try to be a bit more descriptive of what I did. MicroUgly, others, if I did something dumb or inefficient somewhere, please do feel free to point it out.

The size of the highlights would depend, I guess, on the light source. I initially had made them somewhat bigger, but I thought it looked too much like gray/white hair in the end. I'll tweak the hair later, once everything falls into place a little more and I can work on the overall image, not just parts.
Iteration 4: "Let's take a stab at the face."

This is a fairly minor step that took me way too much time because I played with the colors too much (something that, you may remember, is never easy for me - the curse of the colorblind). I ended up using the color pick tool, and averaging it out over parts of the original photo to get accurate colors. I use three base colors; medium, highlight, shadow.
The lines are the same as in the previous draft, set to a width of 0,5mm and a blur of 15. I did end up adjusting the nose on both sides - the lines used to be "on top" of the nose, now they are basically depicting the sides of the nose.
I'll continue work on the skin tomorrow - it'll be lots of fiddling with gradients and blurs.
The left highlight really irritates me every time I look at this posting in the preview, expect it to be gone by the next update. I also think the right (from viewer's pov) eyebrow needs to be moved a little to the left and maybe even a tad down. Or maybe rotated a little... gotta tweak that too.
On the plus side... I think it starts to look human.