The forms are progressed, yet still vaguely articulated, by painting out with a kneaded eraser. This is a painterly process that is akin to underpainting. Traditionally for underpainting in oil Raw Umber or Yellow Ochre is loosely brushed or rubbed on and then the lights rubbed out with a rag or with a clean brush. This is a subtractive approach (lifting out). You want to keep things loose yet still reasonably accurate.
Sharpening the Koh-I-Noor crayon to a point with sandpaper I sketch in the basic facial features and the ear. The soft crayon is a bit tricky to sharpen, it crumbles easily so don’t expect to get a razor sharp point.
In the 7/8’s profile view the inner canthus (corner) of the eye plumbs back of the nair of the nose. Using a plumb line (a thin weighted string) held up to and aligned with the inner canthus will go a long way towards illuminating the vertical placement of the eye, nose and node of the mouth.