Nail files and tools come in many different types, shapes and even grits (coarseness.) If you really want to take care of your nails properly, you really need the right tools. Here is a guide that will explain some of the differences and help you make a better choice.
Metal
Metal files have been around forever, but do they work well? NO! Metal files can weaken your nails and are actually too harsh to use on natural nails. Note: these can be used if you are wearing acrylic nails.
Glass
Glass nail files are very precise, but can be cost a bit more than traditional files. Glass files are great for precision work, but not overall filing. You have to be careful with glass files since they will break if you drop the
Buffing
Buffing blocks have different sides that are different grit grades. This is good because you can use each side for what you need. A buffing block can be a little hard to hold in your hand, but it is a good choice to get almost everything you need in one nail tool.
Emery
Emery boards are usually double sided. Each side is a specific grit size. One side is usually coarser than the other. This is a great everyday tool to have at home and in your purse. A 180/240 grit is the one chosen by most nail professionals. Emery boards do not last long, though, so keep in mind that you will probably need to replace your board every few weeks or so.
Grit
The higher the grit number, the softer the file. Grits start around 80, but that is even considered too harsh for artificial nails. 100 grit is next, but should only be used with acrylics.
180 is the lowest grit that should be used on natural nails. This is good for toenails, but if you have weaker fingernails, go softer. 240 is a good choice for most filing and some buffing.