Shovels are sturdy and dependable, but after several years of surviving the elements and other typical wear and tear, your old shovel may not cut through the soil as well as it used to. Like a good carving knife, your shovel must be able to slice through the ground in order to do its job. Sharpen your shovel regularly to keep yourself from working too hard in the yard.
Place your shovel into a vice on top of a sturdy workbench to hold it in place. If you don't have a vice, position the shovel between your knees and keep it as tight and sturdy as possible.
Scrub off any rust spots with steel wool. Gently rub the surface of the shovel with steel wool until all rust is taken away. Filing a rusty shovel will wear down the file. You can purchase steel wool at your local grocery store or drugstore.
Determine which side of the shovel is the sharp side and which is the dull side. Do not sharpen both sides of the shovel, or you will take away the stability of the shovel. To find the sharp side, gently run your finger along the top of the shovel blade, then the underside of the blade. One side should feel noticeably sharper, and this is the only side you should sharpen.
File the sharp side of the shovel using a 12-inch mill bastard file at a 70-degree angle. File along the natural edge of the shovel, working from side to side, not up and down. You can purchase a 12-inch mill bastard file at a hardware or home improvement store.
Don't press too hard. If the bastard file is new and sharp, it should slide easily across the surface of the shovel. Use the strength of the file to sharpen the shovel rather than your body strength.