Instead of drawing just a single portrait I decided to fill my page with a range of different portraits - all from RedditGetsDrawn.
I've been playing lots of Borderlands 2, working on a comic and arranging images within scribus.
Here's the portrait work:
Line, red line. White background. Two of the reference images were doubles - something different. Grayscale and color added. I saved over the gray scale layer - normally I'm good about saving off each later. I used the palette that I created in GIMP.