When you have finished filling up your gas tank, try turning the nozzle of the hose a full 180 degrees. This will drain a bit more gas into your tank; in some cases, up to an entire half cup that would otherwise be a bonus to the next gas customer.
Once you get into the habit of turning the hose, you’ll find yourself doing it without thinking. That extra half cup that you get each time that you fill your gas tank can add up to a lot of extra gas at the end of the year that you never have known about.