I would recommend a extinguisher with a metal valve over one with a plastic valve, the plastic tends to lose pressure. Remember to use the PASS method.
Pull the pin
Aim at the base of the fire
Squeeze the handle/trigger
Sweep from side to side
Would not hurt to practice on a small controlled fire outside so you know what to expect, fire extinguishers are cheep. People panic in a real fire.
At work we had fire training ever year.
We were trained to only fight the incipient fire (beginning stage).
If the fire is beyond a small fire get out, not worth losing your life over.