Mulch!
Use mulch to retain moisture in the soil and to protect from drying effects of wind and sun. Mulching also helps keep weeds AWAY.
Group your plants
Group your plants into high or low water users to develop an efficient watering system.
Grey water
Recycle bath/shower water or water used in your washing machine [also called greywater] on the garden, but only on plants that are not going to be eaten. Greywater should not be stored and should be used immediately to prevent disease.