Draw your image on a piece of drawing paper with pencil. Draw only the line art. Don't worry about shading or coloring.
Transfer your image to the scrapper board. Place a piece of white chalk transfer paper with chalk side down against the board. Lay the drawing on top of that. Trace over the drawing with a pencil or pointed stylus to create a chalk outline of your drawing.
Rest your hand on a piece of tissue paper when working on the board. The ink smudges easily from the oils on human hands.
Scratch away the highlighted areas of the image first using a small knife or scratching tool. A scrapper board image is not meant to look like the reverse of a photograph, but rather like an ink print. You'll want to expose mostly white areas and leave the black ink on top for shading and outlines.
Scratch at the surface gently with the scratch tool to remove the initial layer of black. The more you scratch over any single spot the more white underneath is exposed. This allows you to create gradual shading from dark to light with practice.
Wipe down the surface of the board periodically to remove the chalk and ink dust. Use a paper tissue. Wiping is better than blowing the dust off, as it can get into the air and irritate your lungs if breathed in.
Paint over mistakes with a felt tip black ink marker. Look for a good quality marker that produces very black matte ink for the best results. Shiny ink or ink that's not quite black will be obvious on the scrapper board. Allow the ink to dry and continue working until your image is finished.