Step 20: Use the remaining lines and shapes as guides to draw the rest of the baboon's body. Simply darken the outer edges of the initial guides using short strokes to create the shape of the body. Keep the strokes short, otherwise the fur will be too shaggy. Add some strokes inside the monkey's body too. Below the tail, draw a curved line made up of short strokes for the bare patch of skin found there.
Step 21: For a cleaner look, erase as much as you can of the initial guide lines. Don't worry about erasing all of the guides. It's okay to leave some behind. Re-draw any final sketch lines you may have accidentally erased.
Final Step: Add some shading to your baboon drawing to give the figure more dimension and volume. Pick the direction of the light source when shading so that the shadows are consistent with it. Shade lightly at first, and then gradually build up to the level of darkness that you like. Vary the pressure on your pencil to get different degrees of tonal value. For a more detailed guide on how to shade, check out this tutorial: How to shade.
Add more value throughout your baboon drawing for extra detail. Use a light value for the bare skin and a medium value for the rest of the fur. Shade the fur using a series of short strokes to emphasize the texture. Use strokes that go in the general direction of the fur. In the monkey's head, they should radiate outward. Separate each individual stroke a bit so that the white of the paper comes through and creates a more fur-like texture.
Shading can be time-consuming, so be patient and take breaks. Remember to pause the video to draw at your own pace. If your shadows blend in too much with the monkey's fur, go back and darken them to make them stand out more. It's a good idea to use reference as you draw for an accurate depiction of a baboon.
Add a cast shadow underneath. This helps to ground the baboon so it doesn't appear to be floating.