Fill a lawn roller ¾ full of water and walk it over the entire sod. This presses down the sod to ensure good root contact with the soil before watering. Keeping the grass moist during the first few weeks is essential. During this time, the grass roots are establishing and growing. Without plenty of water, this process will slow or halt, and the sod die before it takes. After the first two weeks, water the grass a few times a week to keep it from drying out.  Use a sprinkler system to ensure the grass gets evenly watered. Don't wait until the grass looks brown to water it. Do a soil test by sticking your finger into the dirt. If the soil feels moist to a depth of several inches, it's fine. If the dirt feels dry on the surface or to a depth of an inch or two, it's time to water it. Shade-grown grass should be watered less frequently, since it holds dew longer. Water just to the point of puddling, then stop. If the sod lifts up off the soil, it has been overwatered. Mowing before the roots are well established can pull them out of the soil and damage your sod. Wait patiently until the grass is at least 3 inches (7.6 cm) tall, and gently pull up on several areas of sod to confirm it is firmly attached. Once the lawn is ready, mow it down to no shorter than ⅔ of its height, and never below 2 inches (5 cm).  Always be sure the mower blades are sharp, straight and clean, Mow in a different directional pattern each time the grass is mowed to ensure even growth. You can bag the clippings, but leaving them on the lawn will actually improve its health, since they act as free fertilizer. Use the same starter fertilizer to dress the lawn after a month has passed. This is necessary to replace the nutrients that may have been washed away during a month of heavy watering. After the first month, you need only fertilize your grass once or twice a season to replace nutrients in the years to come. Keeping up with watering, mowing and fertilizing your lawn is the best way to grow thick, healthy grass, and it's also the best way to keep weeds away. Weeds tend to move in when the grass gets patchy. They're nature's way of covering up bare spots in the ground. If you make sure there aren't bare spots to begin with, you won't have to worry much about weeds. If you notice an area where the sod seems to be dead, replace it as soon as possible. Tear up the old sod, enrich the soil underneath with compost, and add fresh sod, making sure the seams lay right next to the healthy grass on either side. This will prevent weeds from coming up where the sod is dead.

Summary:
Walk over the lawn with a lawn roller. Water it thoroughly for the first two weeks. Mow once the grass is at least 3 inches (7.6 cm). Fertilize the lawn again after a month. Maintain your lawn to keep it free of weeds.