One of the most common mistakes beginning artists make is not developing tones properly. If an area appears black, especially if the animal has black fur, beginners have a tendency to just fill it in solidly. If an area appears white, they simply leave it empty, allowing the paper to stay pure white.
Both of these approaches are incorrect. Black and white are never pure. They are both affected by light and shadow and are actually various shades of gray.
Look for reference photos of things you think of as black or white. Try drawing them in your segment drawing notebook.
When creating something white, it helps to place background shading behind your subject. The darker tones will help the light show up around the edges of the subject.
This gorilla’s fur is quite dark, but it isn’t black. There is a hint of light reflecting off the fur. I lifted these light areas out with a kneaded eraser. On the darker left side, I filled in the area with pencil strokes going in the direction of the fur, so if the pencil lines show, they are consistent with the surface. Simply filling it in with randomly placed lines just to make it dark would make this area look flat.
Very little of this seal has actually remained pure white. Gray tones make this seal look realistic. The horizontal placement of the shading in the background gives the illusion of distance.
Very little of this drawing has been left pure white—only the highlight areas on the polar bears and the snow. The dark tree trunks appear almost black, but they have highlights from the light coming from the right side.