One easy way to decrease water usage is to install low-flow shower heads. I purchased and installed a Waterpik Eco Flow shower head. I bought the Eco Flow 5 Mode. It uses 1.5 gallons of water a minute whereas our old shower head used 2.5 gallons per minute. This saves water and in turn save you money on your water bills - so it's a plus for you and mother earth. :-)
I've only used it once but so far I'm happy with it. It has five spray modes - one is a pulsing massage and feels great. It also has a "pause" function where the water essentially stops flowing (minimal water still comes out) so that you can pause the water while shaving.
It was very easy to install and came with detailed instructions. I changed the shower head on my own and had no issues.