Wow, thanks that was quite informative.
Something that has been bothering me for a while is that all my work seems to look more or less washed out..
I know I have a habit of de-saturating shadows quite a bit and also using bright outlines.
What you said about pillow shading was spot on..
So I tried to touch it up a bit.
(right one just for lulz)
As for the school girl, your version looks very awesome.
Although she looks a bit like a zombie due to the eyes, or the right eye in particular
But yeah, I see your point very clearly.
My version relies heavily on outlines, while yours uses colors and shades to separate limbs and such.
The strong yet selective outline also does a fine job of adding much needed contrast.
At first I wasn't sure about having the highlights in just a single color, but I think it's growing on me, it's sharper and more effective.
(It's funny how much easier it is to criticize/analyze someone else's work
)