The ink cartridges may be old or low on ink, and you may need to replace them.
Try printing a different document or printing from another application to determine if the problem is limited to one document or to the application. If it is, you may need to recreate your original document (by copying and pasting the text into a new file for example).
Make sure your printer is selected in Windows, or is set as the active printer in Print Center (Macintosh 10.3.x) or Print and Fax (Macintosh 10.4.x to 10.5.x).
Make sure the printer software settings are appropriate for the paper size you’re using.