Try a fairly aggressive automotive polishing compound used for color/wet sanding first. This normally removes the paint and scratches from damage. Panel should look hazy after this. Then apply normal polish and buff to a shine. If this fails, wet sand with 1000/1200 grit sandpaper on a sanding block or other flat surface. Finish with 2000 grit, then use polish. You can buy everything you need at Painters Supply on Santa Fe Dr.