Use cold water whenever possible to do normal household cleaning. Not all showerheads are the same. Low-flow showerheads use less than half the water of ordinary showerheads. They give you a better shower, even if your home has low water pressure. You won't run out of hot water as often.
New showerheads are very easy to install.
Don't fill the tub all the way. Every inch of water in a standard-sized tub uses about five gallons of water. Fix leaky faucets. Repairing a dripping faucet is easy. Install faucet aerators in the kitchen and bathroom sinks.