Another common mistake that some people may make is after they use their generator, they will leave the remaining fuel in the tank not thinking it will cause any issues. The most obvious issue is that if a little spark goes off, with a little gasoline, you have a formula for a fire. But, even past it being a safety hazard, the simple fact is that engines that are met by EPA and CARB regulations will be less tolerant to stale fuel.
What you need to do is get in the habit of emptying your gas tank after each use. As such, if you have any doubts on how long you will need to run the generator, only put in as much gasoline as you deem necessary. After all, you do not want to waste the gasoline as it is not exactly a cheap liquid.