If the stain is wet, use a paper towel to blot (not rub) as much excess out as you can. Then, use some non-acetone nail polish to continue gently blotting until the stain is gone. Alternatively, for dried nail polish, use tweezers or a scraper to get rid of as many crusty bits as you can. Next, wet the stain with cold water, spray it with hairspray and add a couple of splashes of rubbing alcohol. Use an old toothbrush to gently scrub the stain, adding extra cold water as you go, repeating until the stain is gone.