Clean excessive dirt or grime from the wood with a mild, ammonia-free cleaning agent and a sponge. A mixture of soap and water works fine, but remember that if the wood becomes saturated with water it will have to thoroughly dry before moving on.
Dampen a rag with mineral spirits and wipe down the wood. Apply firm pressure while spreading the mineral spirits to work it into the wax. Make two or three passes with the mineral spirits to lift up all remaining wax. When the rag no longer picks up any more wax, allow the wood to dry for a few minutes.
Scuff the surface of the wood with 400 grit sandpaper or a fine scouring pad. The goal is not to completely strip the surface, but rather to abrade it so that the primer will adhere properly.
Vacuum the scuffed wood or blow off the dust with compressed air. Wipe off the sanded wood with a tack cloth or a clean, lint-free rag soaked in mineral spirits to remove any remaining dust.
Apply oil-based primer to the wood according to the manufacturer’s instructions. Latex or water-based primers are not recommended because they do not adhere well to the remaining finish. If the wood has minor scratches in the surface, multiple layers of primer can smooth out the surface.
Apply two coats of paint according to the manufacturer’s instructions. Generally, either water-based or oil paints can be applied, but you should check the label to make sure that the paint is compatible with oil-based primer.