Eradicate weeds from your lawn site. Either treat with an herbicide containing glyphosate, closely following the manufacturer's instructions, or weed by hand. If you weed by hand, remove the whole roots of weeds. Many perennial weeds can grow back from small root fragments left in the soil.
Till the soil to a depth of 9 inches. On large sites, use a garden rotavator. If the soil is compacted, amend with a 3-inch layer of well-rotted compost.
Add a balanced fertilizer such as 10-10-10 to the top 2 inches of the soil, mixing it in well.
Rake the soil, removing any stones that have worked their way to the surface. Go over it with a light roller to eliminate bumps and hollows.
Lay the turf, ideally within 24 hours of delivery. Do not allow the turf to dry out before laying. Unroll the turf and, starting at a straight edge, lay it down as you would a carpet. Lay it in rows, staggering the rows like brickwork. Abut the separate sods so they join snugly without overlapping. Use a sharp knife to cut turf around awkward shapes.
Water the turf as soon as you've finished laying it. Give it an inch of water.