You should keep an extinguisher close enough to an exit so that a fire can't block your escape. But don't mount it right next to a heat source, such as your range; you might not be able to reach it if there is a fire.
For easier access, securely mount the extinguisher so that its top is no more than 5 feet off the floor.
Extinguishers should never be tested; they're single-use products.
If a fire breaks out, one person should call 911 and another should help evacuate people.
To fight a fire, hold the extinguisher with the nozzle away from you, remove the pin, aim low and carefully toward the base of the fire, and squeeze the lever slowly, sweeping the nozzle side-to-side.
Extinguishers should be tagged with the date purchased and be replaced after 12 years.