There are two general procedures to conduct before waxing your vehicle. First, you need to clean your car in small details. Use tar removers, as well as detailing clay, but use it wisely to avoid scratching the body. The surface must feel perfectly smooth. Second, you need to clear small defects with a polish procedure. Check this link for automotive polish and take your time while doing it. If applied correctly, polish products can eliminate small scratches. You might need a professional machine as well. Preparation is obviously the key before applying wax, while a little dedication can work a very long way.