Step 1 - START BY DRAWING A MULTITUDE OF FACES
Your faces don't have to be detailed or complex, only enough to locate eyes, a nose and a mouth. I didn't even add ears to mine.
Step 2 - PLAY
Vary the ways you treat the face. I'm going for a raven, so I tried furled eyebrow lines, a beak, and the top, bottom, and both top and bottom of the eyes. I also played with how the ends terminate. I chose three to work with, and then traced the final in black.
Step 3 - CONSTRUCTING THE DESIGN
Tonight I'll try the make up on a person to see how the design works. I'll make even further refinements as I apply white, gray, and finally the black outline.