Dude, I had a forest in my back yard and the only reason my front was green was because that's the color of the weeds that I have.

I've fertilized, and I put down chemicals (I concur with the all natural approach but these weeds have gotten me to stop thinking like a hippie and go down that chemical path to enlightment). I think I used Spectracide. I waited a week with no results aside from some minor wilting.

I then mowed my grass and watered. The next week I mowed and layed down Weed B Gone, much better results. I waited two weeks, mowed and laid down another layer of chemicals (my yard is obviously addicted). I'm still getting some weeds and some pesky bright green clump of grass that is sprouting up like little insurgents bent upon allan-lawn domination. I pull them out.

Additionally, I've picked up a yard of compost from a place down the street a bit for 29 dollars... go in uniform and get 10% off. Spreading it is heck on the back and arms, but WOW does it make your grass green!!!

Additionally I've put down a bag in the front and a bag in the back of grass seed for that full green summer bloom. I missed the late winter seeding for that early spring bounce back from the winter gloom... although I plan on doing it again this coming fall.

I think there's a lot to lawn care that most people just don't know (myself included, always looking for tips) and others who are willing to chime in with advice.