You might notice in the previous stage that though I added hair on his head, I did not yet place a mustache. That may seem strange, especially considering the size of it. I wanted to wait until value was addressed - his mustache is more clearly defined by the shadow it casts than the hair itself. If I placed that mouth correctly, then all I'd theoretically need is a cast shadow from the mustache and it should give the illusion I need. As mentioned before, contours are not real. They do not exist. It's all about form and the light that falls on it.
As you can see here, a light glaze of charcoal was laid in. It was kept as simple as the light of the paper versus the most basic shadow. All I am concerned with is the overall effect of light and the absence of light, nothing more. This probably took fifteen minutes, and that's all I needed to give the drawing weight. Don't get too hung up on the different variations of shade and shadow right now, just the basic light and dark.