Scrape food instead of, or before, rinsing plates before putting them in the dishwasher
Why
Our kitchen sinks run at 6 or 8 or more litres per minute, so rinsing dishes can waste a lot of water. Of course, if you are rinsing with hot water, energy is wasted as well.
How
By using a rubber scraper to remove food from plates, you can eliminate (or greatly reduce) the need to rinse dishes.