I recently drew this for an art class. I used a graphite base: using a knife to lay down graphite shaved from a graphite stick, and the built up the layers. It's A4 size and i'm pretty happy how it came out. It was really difficult to get the skin texture, whilst maintaining the areas of pure white.
The picture was an elderly artist, from an art magazine, and was really an exercise in tone, trying to match the photocopy as closely as possible rather than produce an accurate looking drawing. This means i couldn't use any artistic license and really had to aim for accuracy, something I don't normally bother with! This is a great way to practice and improve, especially in paying attention to the original and not becoming engrossed in your own work.
It may not be perfect but this was a good project and I'd recommend any aspiring artists to practice their tonal work using photocopies.