Lawns started from seed are best planted in fall, early enough in the season to give the grass time to establish before cold weather comes. The next best time is spring, after all danger of frost is past and before weather turns hot. Do final leveling with a garden rake. Pick a windless day and sow seed evenly, using a drop or rotary spreader. Apply a complete dry granular fertilizer, also using a spreader.
Several manufacturers offer fertilizers formulated especially for starting new lawns.
Mulching is the better option if you expect hot, dry weather or drying winds. Note that it's not necessary to roll the new lawn's surface with a water-filled roller. Doing so can actually inhibit germination, since the roller packs down the soil surface and causes it to crust over. Water thoroughly , taking care not to wash away the seed. Mow for the first time when the grass is one-third taller than its optimum height.