When you first begin to draw fur, it's easy to get lost in all the layers and colors of an animal. I've devised a way to think of fur, that takes the mystery out of the process. See the image above. Imagine it to be a stack of lumber out in the yard. The sun is above the lumber and it casts a shadow around the top of the boards where one board lays against another. As this light hits the boards, the top of each board is lit up where it's closest to the light. Then you see a shadow that's formed when the edge of a board blocks the light from falling onto the next board.
The light has created a pattern of shadow and highlight. This same process will happen in an animals fur.
Lesson two is coming next.