At very best, house fires are expensive to deal with and at worst, they can be deadly. Best practice is to check the charge on your fire extinguisher once a month. To do so, just press the pressure test button and make sure the level is steady. If it isn’t, you’ll need to either replace it or get it recharged.
Around the same time, you should hit the test button on smoke alarms so you know they’re working. Once a year, you should replace the batteries, vacuum around the vents, and spray the outside of the alarm with insect repellant (bugs and spiders sometimes like to nest inside the cover!). If the alarm chirps even after the battery is replaced (*eye twitch*), the entire alarm probably needs to be replaced.