When using a metal file, always remember to bear down on the forward stroke only.  On the return stroke, lift the file clear of the surface to avoid dulling the instrument’s teeth. Only when working on very soft metals is it advisable to drag the file’s teeth slightly on the return stroke.  This helps clear out metal pieces from between the teeth. 

It is best to bear down just hard enough to keep the file cutting at all times.  Too little pressure uses only the tips of the teeth; too much pressure can chip the teeth.  Move the file in straight lines across the surface.  Use a vice to grip the work so that your hands are free to hold the file.  Protect your hands by equipping the file with a handle.  Buy a wooden handle and install it by inserting the pointed end of the file into the handle hole.

These directions show you how to-

When using a file-

When working on soft metals, you can-

Protect your hands by-