Well, when in start drawing a picture and I'm doing shading,I start with a 4H on the lightest areas and gently build up as far as I can go with that pencil without wrecking the tooth of the paper. If I need to go darker, I then go on top of that with a HB, and so on until I get the shade or darkness I need. So eventually you have layers of grades of pencil. Works best on rich skin tones or if the skin is going to be the main focus of the picture x