A good way to see if your lawn needs watering is to step on some grass. If the springs back up, you don't need to water. If it stays flat, it's time to water. Deep-soak your lawn. Water during the cool parts of the day.
Early morning is better than dusk since it helps prevent the growth of fungus.
Properly position your sprinklers. Direct the spray in such a way that water lands on your lawn or garden, not on concrete, where it does no good. Avoid watering on windy days when much of your water may be carried off before it ever hits the ground. Check for leaks in pipes, hoses, faucets and couplings . Even a small drip can waste 50 or more gallons of water a day.