To sharpen skis, you will need skis, a file, and rubber bands. Secure the ski bindings out of the way using rubber bands to hold them down. Sharpen each ski by running the file from tail to tip along the entire edge with constant pressure, repeating several times on each side until the edges feel sharp when scraped against the back of your hand. Check the edge and continue filing until satisfied before enjoying the sharpened skis on the slopes.