If your lawn isn't looking so good ' full of weeds, thin and thatchy, or just plain tired ' renovating will give it new life. Renovation is easier than planting a lawn from scratch and gives you that new lawn look.
Plan renovation so you can reseed during ideal planting time ' early fall or early spring for most typical cool-season grasses, such as bluegrass and fescue.
Kill the whole lawn if it is hopelessly infested with weeds; spray with a broad-spectrum herbicide like glyphosate (Clean-up or Round-up), and wait the length of time recommended on the label before proceeding with replanting. If weeds are not a big problem, you don't have to kill anything.
Dethatch the lawn with a power dethatcher, available for rent at many rental yards.
Rake up the thatch and dispose of it, or add it to a compost pile.
Aerate the lawn with a power aerator, available at rental yards. Leave the dug-up cores (they'll break down) or rake them up.
Level uneven spots by spreading topsoil and raking.
Reseed the lawn with a grass type adapted to your area (see related eHows).
Lightly cover the seed with 1/4 inch of organic matter spread with a cage roller; see "How to Plant a Lawn From Seed." Apply dry lawn fertilizer, and water it as recommended.
Keep the new lawn moist until grass is established. Then water as usual.