Select a well-ventilated area to paint in. Lay a drop cloth to protect the space.
Put the cabinet on the drop cloth. Remove any drawer pulls or other hardware. If it can't be removed, cover it with painter's tape or electrical tape. The hardware can be thin, so use an Exacto knife to carefully trim away any extra tape.
Clean and dry the cabinets. Remove the drawers, if possible. Treat rust spots with rust primer, if necessary.
Prime the cabinets with the metal primer. Use a spray primer if you can find it, as spray painting the cabinet will be easier than using a brush. Priming the cabinet will create a surface the paint can stick to and should prevent future rust.
Allow the primer to dry according to the package directions.
Spray paint the cabinet with your color choice. Use a rust-resistant paint.