If you are going to overseed your lawn or sow seed over bare patches, there is a machine that combines a few steps in the process to save you time and work. A slit seeder slices into the ground and deposits the seeds. This seeds the grass and loosens the soil at the same time. And because the seeds are safely deposited in the ground, they are less likely to wash away or be eaten by birds, saving you the step of spreading straw. You still need to do some preparation before you use a slit seeder.
Mow the lawn short. This will remove the taller grass that might keep the seeds from reaching the soil. It also allows seeds to get full sun to help them germinate.
Rake the lawn to remove grass clippings and dethatch the lawn. Dethatching removes layers of dead grass that is covering the ground near the soil. Removing it helps bring light down to the soil.
Test the soil's pH and add fertilizer or amendments to get the soil to a pH of around 6.5.
Choose a type of grass that will grow well in your area and is suited to your soil type.