Here's another space girl from the Trinquette challenge.
Here's the final:
The original sketch.  I was pretty happy with this.
The colors changed the flow quite a bit.
Here's the first pass. Her jaw felt a little too square in this one.
This was a candidate final:
Here's a closeup of her face.
As I stared at this one of the things I realized was that I didn't have enough contrast in my color values.  So I took another pass at darkening the skin.  I also tried a different background color:
The background color wasn't quite doing it for me though.  It brought out her skin tones nicely, but it also seemed to compete with it.  So for the final I went back to the blue.