To polish most types of acrylic, fine grit sandpapers are the best option alternating between wet and dry. Using a piece of wet, 800 grit sandpaper buff the surface in a circular motion and then repeat with a dry piece of the same sandpaper. Continue alternating between the wet and dry pieces, rubbing for a few minutes at a time. If it begins to look frosty this is just part of the process and these will disappear as you keep sanding. Move onto the grade 1200 paper and continue with the circular buffing motions, before drying to area fully with a soft, dry cotton cloth. If you have acrylic polish, this will help the material shine and look as good as new.