Grass clippings left on the lawn return about 2 pounds of nitrogen to the soil. Spread a quarter-inch layer of compost on the lawn and you add another pound. For many lawns, that's enough fertilizing for the year. Feed right when you do. Apply no more than 1 pound of nitrogen per 1,000 square feet during each application.
Chemical fertilizers green up the grass quicker, but leave the grass hungry for more quickly, too.
Drop that hose. Resist the urge to sprinkle each evening. Frequent watering promotes shallow roots. Instead, give the lawn one good soaking per week and take rainfall into consideration. Crowd out or pull weeds.