Watch those edges

Often your photo or document will slip and skew when you close the lid of a flatbed scanner. For this reason, keep a Post-it note handy. Use it like tape to hold the item flush against the edge of the scanning area. Unlike tape, it won't leave any adhesive behind to soil the surface of the glass.

Although many scanners come with software that can straighten the resultant scan, it is far better to make a straight scan so that reprocessing isn't necessary. There are enough other variables - colour, contrast, brightness, resolution, size, intended usage ... - to worry about without adding to them.