If this was my project, I'd lay down a few layers of newspaper. Then I would rake up leaves and shred them alond with the dead plants you just pulled, lay them on top of the soil. Then I'd add any kitchen scraps I had (except for meat and dairy). I'd toss some soil or compost on, too. Then I'd let the autumn rains and the winter snow work magic and turn those beds into brown gold by next spring.

This is called Lasagna Gardening. It will keep the weeds down and build up your soil so whatever you plant next spring will be very, very happy.

Agreed. I would not bother using any herbicide (the newspaper and other layers will take care of killing what is there) and I certainly would not bother spending time and energy turning the soil. Though I personally would not rely completely on autumn rains: Water the bed well to get it started, and makes sure it stays moist. That way it'll break down faster.

Preen is simply a pre emergent. If you spread preen, then turned the soil, you would be defeating the purpose. Nothing wrong with the above answers. Tell your neighbor about GW so they too can learn how to garden properly.