Use a wet-dry vacuum to remove any standing water on the steps. The lack of standing water prevents ice from forming in any great quantity.
Shovel any snow that accumulates on your steps, since the melting snow freezes into ice if you leave it there.
Scatter deicing salts on the steps. You can use rock salt, calcium chloride or magnesium chloride, which can be purchased at a hardware store, home-improvement store or even at the supermarket. Cover the entire step with a layer of the salt.