Thank you for the comments!
Sharon:
I realized after I posted this that a reference photo would be a good idea, especially for critiques, however I don't have access to this cast at the moment. The photo of the drawing is also a bit 'bleached' out and doesn't offer much detail to comment on.
I recently purchased Harold Speed's books on painting and drawing, but admit I haven't had a whole lot of time to really get into them.
I know. I am a terrible student.
Mischa:
You are right about the highlights. I think the overall drawing is too light given the reference, and it seems to be my general tendency when rendering. I am currently working on a cast of Venus, trying to render things with more structural understanding instead of reacting to value shifts. Not much success there yet, but I will post when I get farther along!
Carol