Clip nails so they're slightly less than a quarter-inch long, says N.Y.C. manicurist Pattie Yankee. Then take a file and round the sides just a bit (don't use one labeled "coarse" because it can cause tears). Be careful not to go any shorter or you'll be begging for an ingrown.
Perfect Formula Petite Crystal nail file, $10; QVC.Read MoreLess