Ok folks, is it fall? What do I do to my weed infested lawn now?
Aerate.
Overseed any thin spots or areas where weeds are heavy.
Fertilize (I use Milorganite).
You can decide next spring if you want to put down some pre-emergent when you fertilize. This would especially help with crabgrass. It just depends on if you want to put down chemicals or not. If you do not want to use chemicals, you can try corn gluten meal.