One thing that I always recommend to folks is to NOT run out the gas, or even run it out of the carb. Matter of fact, I've just gotten into the habit of putting Stabil in my cans before I go to fill them up, so everything that I run has Stabil in it all of the time.
With the ethanol in the gas, and all of the plastic and rubber parts associated with the newer fuel systems and carburetor parts, the ethanol is very corrosive once it comes in contact with air and over time is allowed to oxidize and break down. It is better to keep the carb full so there are less parts exposed to air, and less oxidation surface area. I know that it is one of the biggest service items in our shop in the spring time, folks that ran the mowers completely dry, then when they went to start them in the spring, the carbs are all messed up.