Remove all the bathroom supplies and items in and around the vanity. Put a dropcloth on the floor around the vanity.
Remove doors and shelves from the vanity if possible. This will make it easier to reach some of the nooks and crannies on those pieces.
Sand the vanity and the pieces you were able to remove with medium grit sandpaper. Clean the vanity with a wet rag, and dry it with an old towel.
Place painter's tape around the vanity edging. This will save you from having to remove paint from the edging in the future.
Paint the vanity with primer. This will help the paint stick to the vanity. Wait for the primer to dry completely.
Paint the vanity with a paintbrush and high-gloss paint, which will have a shiny finish. Use a small paintbrush when necessary to reach the small parts of the vanity.