Watering frequently can actually damage your lawn. A good way to see if your lawn needs watering is to step on some grass. If it springs back up, you don't need to water. If it stays flat, it's time to water. Deep-soak your lawn.
Early morning is better than dusk since it helps prevent the growth of fungus.
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. Even a small drip can waste 50 or more gallons of water a day. Larger leaks can waste thousands of gallons. Less than 12 - means you need to change your water conservation habits.