Check water requirements of different models/brands when purchasing a new appliance. Some use more than others.
Check all water line connections and faucets for leaks. A slow drip can waste as much as 170 gallons of water each day, or 5,000 gallons a month, and will add to the water bill.
Learn to repair faucets so that drips can be corrected promptly. It's easy to do, and can mean a substantial savings in water and plumbing bills.
Check for hidden leaks such as between the water meter and the house. Turn off all indoor and outdoor faucets and water-using appliances. The water meter should be read at 10-20 minute intervals. If it continues to run, a leak probably exists.
Insulate all hot water pipes to reduce delays in waiting for the water to run hot.
Be sure the water heater thermostat is not set too high.
Use a moisture meter to determine when house plants need water. More plants die from over-watering than from being dry.