Put a layer of mulch around trees and plants. Chunks of bark, peat moss or gravel slow down evaporation. If you have a pool, use a pool cover to cut down on evaporation. It will also keep your pool cleaner and reduce the need to add chemicals. Set lawn mower blades one notch higher.
Longer grass means less evaporation.
Water your garden or lawn during the cool parts of the day. Early morning is better than dusk since it helps prevent the growth of fungus. Shorten your showers. Run only full loads in the washing machine and dishwasher. Regularly inspect for leaks.