1. Create a value scale with 5 levels from solid white to solid black (or other hue). This scale will be used for reference. 2. Choose image and create stencil to trace. 3. Trace image many times to create layering effect. (There is no set number of how many outlines are required - keep in mind composition and time management) 4. Begin to shade your shapes to create depth. The background (or bottom) should be the darkest, and continue to get lighter as you move to the nearest/surface/top layer.
See examples below for more examples of how to alter this project if you choose.