It is best to file your nails only when the white part of the nail-the tip-has grown ¼ inch from the nail's stress point, which is where the free edge meets the pink part of the nail plate. If you file your nails before this point, it can weaken them. At the same time, if you let your free edge grow longer than the nail plate, it is certain your nail will break. Do not file from side to side, which can weaken the stress points of the nail's free edge. Be sure to go from corner to center in one direction, using the groove on the side of your nail as a guide.
Choosing a File
Stay away from metal nail files since they are very harsh and can even split nails. One wrong swipe and you've ruined your nail shape. Most manicurists recommend a soft, straight file that won't cause any damage if you swipe it the wrong way.
Shaping the Nail
There are many ways to determine your nail's shape. Many people want to have their nails cut square, which may come from the belief that square-cut nails are stronger. This is a myth-in fact, if you shape them correctly, all nail shapes are equally as strong. If your cuticle is oval shaped at the base, the square look may work for you, but if you have a pointed cuticle, you may want to go with a more oval-shaped nail. Now, the trend is a softer shape.