Use a screwdriver to remove the screws holding the cabinet doors to the hinges. Completely remove the hinges and set them aside with the screws. Lay the bathroom cabinet doors on a flat surface.
Sand any part of the cabinet that you will be painting with 150-grit open-coat sandpaper. Follow the grain of the wood. Sand only until the shiny coating of the previous finish or laminate is dull.
Sand the cabinet doors that you removed. Sand them with the same sandpaper and in the same fashion that you sanded the cabinet body.
Attach a brush attachment to your vacuum cleaner. Vacuum the surface of the cabinet doors and the cabinet body to remove the dust from sanding.