So here is a shot of me working out the drawing in blue pencil. I then went over it with regular graphite, and shaded the hair and background to create a basic texture. I did not shade the face, and instead did all of the rendering while coloring in Photoshop. That's an enlarged printout of my initial thumbnail sketch on the left. You can see where I used some markers to roughly work out how I wanted to render the lighting, which I kept in mind while drawing.
Since it was such a close-up shot, I worked at a slightly smaller scale than I normally would for a comic book cover to help me deal with the proportions.
Above is the final graphite drawing. Now, I know I said I didn't shade the face, but it looked unfinished, so I went back in with additional inkwash shading after the fact, just to complete the image. The paper I used wasn't really suited for this approach, but it was fun to do nonetheless.