Depending on how rough it is, sand starting with 600 grit and working up to wet sanding using 1,200 to 1,500. Use a small spray bottle with water and a drop or two of dish soap. After you have reached the desired finish use a high grade automotive clear and apply 2-3 coats, sanding between coats with 1,500 to remove orange peel. Wet sand last coat just to remove the shine and hand buff to a shine. Be carful when sanding, you can sand through the clear very easy around the edges.