More advantages of using shredded fall leaves as mulch:

• They are free
• Mix with some used coffee grounds from you local Starbucks and you have created earthworm heaven. Mulch generously and you will allow them to stay closer to the surface during the winter.
• Weeding in the spring will be a snap.
• By the time you plant tomatoes, peppers and beans most of it will have turned to compost. So much so that by mid to late June you will need to re-mulch to keep your beds cool, moist, and weed-free.

Mulching enriches the soil by giving it nutrients. This is another big advantage of mulching. When you perform mulching on your soil with organic material, the decaying organic mulch provides nutrients to the soil and improves the fertility of the soil. This means that the crops that you grow on such a soil are going to do very well.

If it's in great need of organic matter, I would either dig in or lay compost on top. Then mulch over that for the winter. Worms will come up for the compost when it's not freezing cold, and the mulch will moderate the temperature and keep things moist. In spring you can decide whether to dig everything in, or plant through the mulch if you're planting a small number of larger plants, or you can rake away the mulch first, plant and re-mulch.

another vote for fall mulching

you wont let your soil go bare into winter

I totally agree with nevermores excelent advice

I was thinking that too. Especially if your soil is compactible, like clay, it will be better to have it covered against pounding rain and such. A mulched bed will be more fluffy in spring.

"You wont let your soil go bare into winter."

Bare soil is the Devil's playground, I always say.