Filling your nails the right way involves more than just going in one direction. Invest in the right tools and pay attention to the shape of your nails. Your efforts will result in nails that are clean and snag-free.
The Right File
Emery boards are cheap, convenient and easily replaceable, but they're not the best tool for filing fingernails. Instead, invest in a crystal file, which is more gentle on your nail tips. A crystal file features a fine-grit surface that minimizes splitting and eliminates snags. Although it is a bit more expensive than an emery board, a crystal file will last much longer.
The Right Direction
Choose a shape and begin to file the corners of your nail in one direction and toward the tip of your nail. Once the nail begins to take shape, file the other side of the nail using the same technique. As you finish off the nail, file the tip gently and in one direction. Do not use a sawing back-and-forth motion, as this may split and weaken the nail, and take your time for the best results.