There are so many types of water heaters that it's important to follow manufacturer directions regarding any maintenance, but there are a few things to be aware of that should be inspected often.
Storage tank upkeep
Open the drain valve at least twice a year, letting water run into a pail until it is visibly clear. You should remove about five gallons. Doing so will prevent sediment buildup.
Replacing the anode rod
This is a crucial maintenance step that experts say is rarely taken. The sacrificial anode rod should be checked every year to make sure it hasn't been eaten away or completely covered with scale. A rod will last 5 to 10 years on its own, but cleaning will prolong the lifespan. If the rod isn't attracting corrosion-causing materials away from the tank, the tank will begin to corrode.
If you find all this confusing or feel it's too time consuming for a non-expert (and many do), talk to a local repair company or dealer and schedule inspections and maintenance at times that are convenient for you. Water heater rentals or leases are another way to go about it and let someone else do all the work.