VERY CAREFULLY!!!
Specificly, here are some hints:
Select sturdy cans designed for storing fuel. This gets you a container that is safer than a water jug, for instance. It should be red and plainly marked: "GASOLINE" . What ever you do, do not mix them up with containers holding kerosene, deisel fuel or water. Putting gasoline in a kerosene auxiliary heater can be a "devistating" experiance.
Five gallon / 20 liter cans are the largest to consider unless you have a pump. Even this size can be a handling problem filling a generator or other small appliance, so I suggest one or more smaller containers also be included.
Have the proper size spout and also include a funnel for the small fills.
Add a stabilizer, such as "Stabil", available at most auto supply stores.
Tag the cans with the fill date and indicate whether or not a stabilizer. I usually don't add the stabilizer when I plan to use the fuel shortly, i.e. a couple of weeks.
Store in a garage or other outbuilding, not in the basement. The storage area should be well ventilated, away from any heater. Keep seperate from other fuel containers. It should also be locked to keep the curious and dishonest away.
Container storage in a vehicle is also a potential danger. I use a couple of GI fuel can holders bolted to a 2X10 which fits into slots in the back of my truck. In any case, secure cans, even for a short ride home. Use rope, bungees, whatever, to prevent spills.
Rotate the stock a couple of times a year.
As far as how much to store, it depends.......? I use gasoline regularly for a tractor, riding mower, chain saw etc., so I buy and store more than most.

"There is nothing more frightening than ignorance in action"