Use a mechanical pencil or a "stippling" motion for subtle skin texture.
Use a kneaded eraser to "pull" light back out of dark areas for a glow. Secrets to Drawing Realistic Faces
Drawing a realistic face is less about "talent" and more about training your eyes to see shapes rather than symbols. Most beginners fail because they draw what they think an eye looks like, rather than what is actually there. Master the Proportions Use a mechanical pencil or a "stippling" motion