Pull out any roots, weeds, stones and obstructions in your lawn. Use a spade to churn and loosen the soil. Ideally, till the soil to a depth of 18 inches.
Mix in a bag of compost, rotting manure or peat for every 100 square feet of lawn. Rake out the surface until level.
Choose the right grass seed for your environment. For example, use shade-tolerant Kentucky Bluegrass for partially shaded lawns, or 50 percent Kentucky Bluegrass with 50 percent perennial rygegrass in high sunlight areas, according to the University of Minnesota. However, species and type will vary according to your region.
Spread the seed out evenly across the entire lawn area.
Mulch the entire seedbed with weed-free straw. Use one bale for every 1,000 square feet, according to the University of Florida. This will keep the weeds down and the moisture in.
Water the area with a sprinkler, or a watering can for smaller lawns. Water deeply every day, but don't allow the topsoil to get boggy or sunken. Different species and climates require different watering levels.
Let your new grass grow long and bushy to at least 3 inches before mowing so that you don't damage the root bed.