Mix organic compost into the top 4 inches of soil using a rototiller. The compost-to-topsoil ratio should be 1-to-1.
Add earthworms to your soil to help amend it. Earthworms can be purchased from your local agricultural Extension office.
Wait a week for the compost to settle and the worms to naturally aerate the soil before determining if you need to manually aerate it.
Loosen the soil with a manual aerator if the worms have been insufficient.
Sow grass seed into the aerated soil. Rake the soil to cover the seed and water with a garden hose.
Water frequently for the first two weeks while the grass seed takes root. Thereafter, water deeply only when the grass is threatened by drought.