Check the pH and nutrients in the soil with a soil testing kit from a garden center, nursery or university extension office.
Spray post-emergent herbicide on weeds in the area where you are placing sod. Follow the directions on the label and repeat if necessary.
Remove rocks, large roots, tree stumps and construction debris from the yard.
Scrape the topsoil off high areas in the yard, using a shovel and spreading it around evenly, or use it to fill in low areas if needed.
Rototill the yard to a depth of 6 inches to loosen the soil. Remove any rocks and debris as necessary.
Add lime, peat moss, compost or other amendments needed to the soil. Use the rototiller to work the amendments into the soil to a depth of 10 to 12 inches. Let the soil settle for two to three days after tilling.
Install sprinklers or another irrigation system 12 to 18 inches underground.
Firm the topsoil with a water ballast roller. Look for dips and humps in the yard and fill or level them. Rake the yard to help the sod root easier once laid.