Sand the shelving with fine sandpaper to roughen up the surface. Use a fine sanding block or electric sander.
Wash the shelves using trisodium phosphate, a bucket and sponge. Rinse with clear water and dry thoroughly. TSP is designed to clean even the residue from previous cleaners, leaving an unblemished surface.
Apply a primer designed for use on vinyl. These are available in spray cans or you can paint it on with a paintbrush. Allow the primer to cure according to the manufacturer's recommendations.
Paint the shelf with a 100 percent acrylic latex paint. The best type of paint has Emulsabond added to it, which allows the paint to stick better. Spray the paint onto the shelves or use a paintbrush. Allow it to cure according to the package instructions and then apply a second coat.