Fill a plastic spray bottle with a small amount of vegetable oil.
Spray the concave side of the snow shovel liberally with vegetable oil. Go outside to avoid making a mess in the house.
Shovel as usual. The snow should slide right off of your shovel when you pitch it to the side, and you'll avoid accumulating the snow particles that eventually weigh shovels down and make them too heavy to use comfortably.
When you're through shoveling, wipe down the surface of the shovel with a dry paper towel to avoid a grimy buildup.