shape the top parallel to the cuticle. that's very important, don't care about the shape of the nail line, it can be deceiving. While filing, turn your hand over and look from behind. That gives you an idea about the nail shape, too. Use a toe nail clipper to clip the top parallel to the cuticle line, then file with a glass/crystal file, always going in the same direction, not back and forth. Filing back and forth can damage your nail, causing it to split. Then round the edges using the file, they shape very easily. Phew, that was a lot =D