My friend is an illustrator and has lot of sketches that she wants to digitize to put online. She is also working on a children's book.
How should she scan the images and what are some beginner steps that she can take to clean them up once digitized? I'm guessing the clean-up will be necessary just from the scanning process.
Are they line drawings or shaded drawings? If they're line drawings, the most common method is to scan as Black and White, trace the artwork using the pen tool (or freehand strokes with a brush) on a different layer, and work from there.
If it's shaded drawings, she should consider scanning either as greyscale (for black and white drawings) or full color (for color shaded drawings) and go from there. Depending on her comfort level with Photoshop / Illustrator, she could do her shading in Photoshop or Illustrator (multiple tutorials exist online for this).
Keep in mind that photocopy-invisible blue pencils ("no-repro blue") will often be picked up in a greyscale scan, so if that's a technique she uses prior to inking the blue lines may still show up.
As mentioned above, there are a some things to take into consideration before scanning. Are they just line art? or are they shaded? or are they in color?
Line art = Scan as black and white
Shaded = Scan as greyscale or color then desaturate in Photoshop
Color = Scan in color
I try to always scan at 300dpi that way if you need it for print later, you don't have to rescan. You can always export it for web @ 72dpi.
If you scan it in Black and white or greyscale, bring it into photoshop and adjust the brightness and contrast (usually bump up both a little) and it will help to make the background completely white w/ no paper texture/fiber/etc. This way you can easily drop it onto a background by setting the inking properties of that layer to multiply.