Here’s another painting exercise that I learned from Paul Souza, who taught the “scumbling the lights” method on a previous post.
As you look at a real posed model, try to analyze the head in terms of simple planes.
State the lines bounding the planes in pencil on chipboard. Seal the board as before, and apply the white oil paint with a bristle brush in varying degrees of thickness until you get the relative tone just right. Leave the shadows untouched by the paint.
I recommend that you use this plane breakdown as a guide. Both the forehead and the upper lip are divided into three planes. The chin and the nose each end in a flat shape.
The same analysis, in varying proportions and angles, can describe very different face types. If you try this plane analysis, and it just doesn’t fit the face, try an alternate breakdown, but keep it simple.
It should look like a puppet being carved from wood, as was stated in the Carolus-Duran post recently.
Seeing forms in simple terms helps you to draw or paint them better. As you proceed with a real portrait, you can subdivide the planes and blend their edges. If you establish a portrait in these terms at the beginning, you’re much more likely to get a three-dimensional appearance and a good likeness.