Avoid changing the thermostat setting frequently. Have your thermostat placed on an indoor wall in the place you spend the most time in your home. It should never be placed by an outside door. Consider installing an automatic setback thermostat from a qualified heating contractor. When you shower, keep it short.
Showers can use less hot water than baths, but only if they're short in duration.
Consider installing low-flow showerheads and faucet aerators. Both can cut water flow without affecting the quality of the water stream, and can save on your water heating costs. A cold water rinse is always appropriate. A hot water tap, dripping once every second, wastes a tankful of water each week. Set your thermostat dial at mid-range.