It wouldn't hurt to send samples off to the state extension and get a soil test done. As far as the weeds you can either start pulling them, smothering them or if you have no objections to weed killer then that would be quicker. Either way after that is done a good choice would be to lay down some wet newspaper on top of the soil and add at least 3 inches of compost. If it's a smaller garden you might get buy with bagged compost or if you have a truck available you can buy bulk compost.

On top of that a layer of leaves or shredded leaves would be good. Then just let that rest until you're ready to begin in the springtime.

I was just checking on cold temperatures and herbicide use.

Linked below is some information.

. . . above 60F, they say.

Steve

Here is a link that might be useful: Herbicide Use During Cold Weather, North Dakota State Univ.