Familiarizing yourself with some key home components and the servicing of them can save time in an emergency and money from service failure.
Locate service controls 
Main water supply. One of the three most important services entering the home. Often found in the mechanical room, in a crawlspace. under stairs at the front of the home, sometimes inside the wall nearby a hose bib at the front of the house. Identifiable by a handle or lever shut off nearby a “PRV”.  Find it, identify it, and test it. Repair or replace it if it shows signs of dripping or isn’t working at all. Keep the area around and access to it clear. Other shut offs are under (should be) each sink and by each toilet. Dishwasher shut offs are usually inside the sink cabinet. Fridge shut offs may be behind the fridge. Washing machine shut offs may be behind the machine or inside a nearby cabinet. Change old rubber hoses for new braided ones.
Electrical panel
May be more than one in a home. May be located in a garage, laundry room, mechanical room, etc Familiarize yourself with the breakers and what they control. Label of not done. GFCI breakers or GFCI outlets in bathrooms and kitchen (how to work them – resetting / split breakers
Main meter – location. How to turn  off in an emergency
Individual appliances – furnace, HWT, boiler, stove, fireplaces, etc
Clean / replace furnace and HRV filters
Clean out dryer ducting. Replace of plastic
Clean bathfan exhaust and stove hood fan
Safety / Security
Inspect / replace fire extinguishers. Gauge should be in the green. No gauge – have professional inspection or replace. Can last 5-15 years but there’s no way to know if it’s 1 yr old or 13 if it doesn’t have a placard. Smoke detectors / CO detectors. Check dates for replacement. Change battery. Add new ones in sleeping rooms. Replace any electrical outlets or switches with scorch marks or loose  or not grounded. Re-key locks and hide a spare, or change locks to keyless. Include storage sheds. Alarm – change access codes and have system inspected for competency. Change system if necessary.
Steve Seaborn