Why is my printer printing in the wrong colors?

Check that all cartridges are properly installed in their correct color slots.
Check to ensure that all cartridges are full, and replace any that may have inadequate ink levels.
Clean the print head using a specially formulated printer cleaning fluid or replace the print head altogether.
Perform a printer power cycle to reset any existing errors.
Reinstall the printer driver (or update the software if prompted to do so).
Ensure that the color settings in the application or printing software are set to the correct color.