I have owned my house for 5 years and have complained about the crappy lawn in the backyard. Well, I finally did something about it. I used our family's 3HP rototiller to tear up half the lawn, added sand and compost and seeded the ground with clover yesterday afternoon.
Why add sand and compost? Since the soil is very compact and has lots of clay in it, adding sand and compost will loosen the soil to help promote better root growth.
Why plant clover? Clover is a green fertilizer meaning that it will lock nitrogen into the soil, which is essential for root development. In August, I will till the whole yard under and possibly plant some grass at that point or a second batch of clover and seed a new lawn next year. Clover is also very good to get rid of grubs (which eat grass roots for lunch).
I will post a few pictures of the lawn as it develops. The germination time for the clover is 3-10 days depending on the amount of water the seeds get.