You should use a tripod, one that can be adjusted in various positions. If you're taking a photo of a photo on a table, for example, the tripod should be able to be adjusted downward. Then use the self-timer to trigger the shutter button (you will need to lock focus first).
A tripod will also let you use small aperture numbers (f/8-f/11), so you can get a deep depth of field for better image sharpness.
Other tips:
- have your camera at least 8-12 inches away from the photo and zoom in with the optical (not digital) zoom.
- set up the photo in a place so as to avoid glare if it's surface in glossy or semi-gloss.
- use as much external lighting as possible; it is preferable than using the flash. Adjust white balance if you must use a flash and diffuse the light by taping transparent plastic over the flash (say, from a milk jug or other translucent material)
Related reading:
Depth of field
http://www.digicamhelp.com/taking-pictures/depth-of-field.htmTripods
http://www.digicamhelp.com/tripods/index.htm
