Unscrew the door handle from the door with a screwdriver. Remove the door from the hinges if you prefer. You can paint the door while still on the hinges, but it can be more difficult. If you decide to remove the door, place it on two sawhorses. If you don't remove the door, cover the hinges with painter's tape.
Remove dirt, grease and other debris from the door. Use a degreasing cleanser and a rag.
Cover windows on the door with painter's tape and newspaper. Tape any areas of the door that you do not want painted.
Prepare the door for painting by applying primer. Apply primer with a paint roller and a paintbrush. Wait until the primer is dry before painting.
Coat the front door with paint. Use a paint roller to cover the main area of the door and a paintbrush to get into hard-to-reach areas. Give the door time to dry and then re-coat with another layer of paint as needed.
Reinstall the hardware when the paint has had several hours to dry.