Make sure the printable side of the paper is faceup. It's usually brighter or whiter.
Select a higher Quality Option or Print Quality and turn off High Speed and Fast Economy or Economy mode in the product software.
Select Photo RPM for the Quality Option (Windows) or Print Quality (Mac OS X 10.4 or Mac OS X 10.5 and 10.6). Remember that this setting increases print time.
Align the print head.
You may need to increase the image resolution or print in a smaller size; see your software documentation.