Adding Eye Coloration:
Use the edge of the shader pen to darkly strengthen the lines surrounding the eyes, the top of the mustache and beard, and the lower half of the eyebrows.
Shading the Face:
The shading falls along both sides and the bottom of the nose, on the inside corners – nearest the nose – of the cheeks, and along the bottom of the eye pad under the eyebrows. You can also add shading to the top of the mustache and beard.
Shading the Leaves in a Pale Tone:
Following the photo below, shade in the background leaves with a pale-medium tonal value, using the side of the shader pen. Make the areas that are deeply tucked under the face or under another leaf fairly solid in tonal fill. Allow some unburned areas in each leaf as it reaches the outer edges of the pattern.
You can use either a scrubbie stroke or cross-hatching stroke for this step.
Second Leaf Shading Layer:
Using your shader on the crisp edge, burn in the leaf vein lines. Outline with the shader pen along the leaf edges where necessary to visually separate one leaf from another. Do not completely re-outline the entire leaf. Only work those areas that need strengthening.