Hate wasting water while waiting for the morning shower? Turn on your clothes washer to hot, allow cold water to collect in the wash tub until it begins to warm. Save it for the next load of clothes, hastening the hot water shower. Works for hand washing dishes, too. Or, put a pot on the rinse side to catch the cold water before filling your dish pan when the hot water shows up and the pan is on the stove warming, or in the microwave, to heat rinse water.
A little more hands on? Keep a bucket handy for the last of the bowl of rinse and wash water to use on plants or washing outdoor tables. Teach the kids these tricks and they can carry them on to adulthood.
And if you just can't turn off the water as you brush your teeth, use the hot water handle first, the initial cold water for brushing and then the hot for shaving. Obviously this isn't much, but one would be surprised just how much gets lost while waiting for hot water.