Remove the doors from the cabinets, unscrewing the hinges. Unscrew the door handles or door knobs from the doors. If you are not getting new doors, label each door with a number in a spot that won't be covered over. Mark the cabinet the door belongs to with the same number.
Wipe the inside and outside of the cabinets with hot, soapy water and a rag or sponge. You want to remove any spots or stains. Also wipe down the doors if you are not replacing them.
Sand the surface of the cabinets and doors. If you plan on painting the inside of the cabinets, sand that area as well. You can want to create a rough surface so the primer will stick to the cabinet.
Apply a coat of primer to the doors and cabinets. Allow the primer to dry for at least four hours, then apply another coat and let dry overnight.
Paint the cabinets and doors using oil-based or latex paint. You can also use a paint specially formulated for use on Formica surfaces. Use the paint roller to apply paint to large areas of the cabinets and doors and a paint brush to apply paint in any small crevices. You want to apply the paint as smoothly as you can, without leaving brush strokes. Let the paint dry for at least four hours.
Screw the doors back onto the cabinets, matching the numbers on each. You can also invest in new glass doors that match the new paint color and attach those to the cabinets.
Attach the hardware to the doors. If you get new handles, make sure they line up with the holes already drilled into the door. Insert the handle or knob into the hole(s) on the door. Finger tighten the screw on the back of the door, then use a screwdriver to tighten fully.