Paint hair as a simple shape.

Shadows should be solid, yet recede.

Make the first brushstrokes on the face colorful.

Flesh loses color as it turns under forms.

1. As you’re doing the face, use the same amount of paint for both cool color and warm color.

2. The muzzle (the area between the nose and mouth) should start to lose color. Put in some raw umber as a cool color and repeat the raw umber on the side plane of the face.

3. If the face in your portrait lacks solidity and the light seems to come through the shadow area, drop the value of your shadow to block that light. Shadow has to look dense enough to appear solid, yet transparent enough to recede.

Painting instruction from Oil Painting Secrets from a Master
by Linda Cateura (p. 98)