Diana...I would spray with a good Rustoleum paint
Do you mean metal cabinets, like a file cabinet or kitchen cabinets . If it is file type , I would clean it well, lightly scuff with a sanding sponge and use a spray paint meant to be used on metal , rustoleum makes one .
If the cabinet is steel (magnet sticks) then sand any uneven areas, bondo and sand dents, then spray with a rattle can like rustoleum. If it isn't ferrous, then I would recommend using a DTM acrylic paint (direct to metal)
Diana, Sand the cabinets lightly. Use a metal primer and then metal paint, let dry completely, and give it a second coat. Aloha!