Good advice.
What always amazes me are the number of people who have generators, and they only have 5 or so gallons of gas on hand (some with less). They run their generator when the power goes out for a few hours, and then are amazed it uses gasoline. So they drive to their nearest gas station, and find out the power is out there too and the pumps don't work. So they drive some more. And drive some more. Finally, they find a gas station with power. And then they are amazed, angry, and hurt that there are huge lines with people trying to fill their cars and gas containers.
Realistically, I believe you need about 25 - 30 gallons on hand. I keep mine with Sta-bil in 5 gallon containers.
I put the date filled on each container, and use the oldest gas first for the mower, leafblowers, etc. You can pour it into your car's gastanks and get fresh after 6 months to keep the gas new.
A relative of mine when out after Sandy looking for red gas containers, because he only had 2 gallons of gas for his generator. When the generator went out, his wife freaked out and told him to get more gas. He went to every hardware store he could find looking for gas containers. They laughed at him.