I had a similar issue, we bought our house this past October. Our's was a little better, but not enough to my standard. What I did and I recommend you do, is rent a thatcher. Thatch the whole lawn. Get a rake. Rake up all the dirt. Get starter fertilizer (anyone that is OK to put down after seeding). Once thats done get a GOOD seed. Pennington or something along those lines. Over seed the hell out of it and water at least once a day for a few weeks. Believe it or not, thatching the lawn will make a huge difference in a few weeks alone. Re fertilize again in about a month. Right now my lawn looks 100% better. Not fully there yet, but getting there.