See if any of these help.
- The more light you get the easier it's going to be to get a sharp image (the shutter speed will be higher)
- Keep an eye out for shadows ... even a slight difference across the page will show on the computer; this can be avoided with some patience
- Try and take the photo so that the camera is on the same plane as the paper
- A bit of zoom may reduce lense distortion
- Take your photo from as stable position as you can, better if you can use a tripod or rest the camera on something fixed. Failing that go for one of the standard body tripod tricks (e.g. kneeling with one knee up, elbow on knee, camera in hand)
- If your camera wants to flash then you're not getting enough light, wait until later!
- Fill the camera's view finder with the paper. It's most likely that your camera uses an averaging method by default for choosing it's mid tones ... filling the view finder with the page should help you get the best result (when using the automatic settings)