Rake the entire lawn vigorously with a garden rake. Remove all tangled stems and other debris from the lawn with the rake and bag the gatherings for disposal.
Pass over the entire lawn with a dethatching tool, either a hand-held model or an automatic one (especially helpful for large areas). Dethatching removes debris trapped in the upper layers of the soil. Remove the thatch once it has been drawn to the surface by the dethatching tool and bag it for disposal or set it aside to be used as compost.
Aerate the lawn. Use an automatic aerator and go evenly across the entire lawn, removing plugs from the soil to allow water to seep deep and reach the grass's roots.
Pour a 1/4-inch layer of gardening soil over the lawn. Spread the soil evenly with the garden rake. Lightly water the soil with a hose or sprinkler system.
Spread grass seed with an automatic spreader. Consult the directions with the type of seed you use and set the spreader accordingly.
Spread fertilizer over the lawn with an automatic spreader. Use a fertilizer without a pre-emergent, which stunts the growth of new seedlings.
Rake the lawn with the garden rake and water the lawn thoroughly.
Mow the lawn regularly to keep the new grass blades to 2 inches or lower for the first 6 weeks of growth. Water the lawn according to the weather; keep the soil moist.