Which (eyes, nose, hair) gives you the most trouble?

Use a blending stump or tissue, but don't overdo it, or the drawing will look "muddy."

Real skin isn't perfectly smooth; it has pores, wrinkles, and imperfections.

The corners of the mouth generally line up with the centers of the pupils. Focus on Value, Not Lines

The top lip is usually darker because it tilts away from overhead light.

Use gradual transitions to create the illusion of curved skin.

Use a mechanical pencil or a "stippling" motion for subtle skin texture.