Water consistently and thoroughly or don't water at all. Tree-shaded areas will stay moist longer, but in late summer and early fall the tree roots may rob the surrounding grass of moisture, so you may need to water these spots more often. Lawns can survive without feeding, but fertilized lawns fight weeds better and look better. Apply the first feeding when spring-flowering bulbs are blooming. A second application can be made in late June or early July.
Some manufacturers offer a four-step fertilizing process, with recommendations on when to apply.
For a green lawn, choose a fertilizer high in nitrogen. If you're nervous about using fertilizer, try applying half the recommended amount the first year.