
click to enlarge
As pencil marks don't always show up well in scanned images, it is recommended that you use pencils for sketching and then use ink or markers to prepare drawings for scanning. Unfortunately, some of the pencil marks you've created may show up in the scanned image if you used a standard pencil. Erasers may not remove all of the pencil marks and can damage the paper as well in some cases.
To eliminate this problem, buy non-photo blue pencils; these light blue pencils are designed in a shade that black-and-white scans won't pick up. Make all of your sketches in non-photo blue, then use a black pen or marker as you normally would.
Scan your drawing in black and white (generally referred to as a "monochrome" or "black-and-white line drawing" setting in most graphics programs). Your black ink or marker drawing will scan perfectly, and the blue sketch lines you created won't show up.
Image Credit: All images by J. Edward Casteele, used with permission.