Now is the best time to add amendments to the soil in the form of just about any organic matter you can get. Manure, leaves, straw, compost, coffee grounds, kitchen scraps, all work their magic in making the condition of the soil much better by spring if they are allowed to rot over winter. (You don't say where you are so remember that cold climates will affect how fast these things break down over winter.)

Straw is good but if you don't use a mulch, remember that it can introduce weed seeds. It's also excellent as a mulch next year (put it down about 6" deep) to keep down weeds and retain moisture. And as it rots, it adds to the soil.

Any of these can be tilled into the soil now or just placed on top in what's called lasagna gardening or sheet composting. It's a good idea to leave something on top of the soil over winter to prevent erosion. If you're in a warmer area, you could also plant a green manure crop now and then till it under in late winter, before it goes to seed in the spring. If that's the case, check with a good garden center or your local cooperative extension to see what would work best in your area. It's too late to plant it in the colder areas.

If you haven't had a soil test done, now is a good time, especially to see if the pH needs adjusting. That's a process that takes awhile so adding lime or other amendments now to change the pH if needed is best done in the fall. Wait until spring to add any fertilizers.

And it's the best time to request seed catalogs. They make the very best winter time reading! Last year a lot of seed companies were just swamped with orders and often delivery was delayed by several weeks. If you order seeds, be sure to do it early next year.

Good luck. As you can see, the so called "dead" season for veggie gardens is far from dead!

Sandy

Sandy has done a great job summarizing the major tasks required at this time of year. I will only try to add some depth into some of the items.

1. Organic matter - unless you have a special organic soil (e.g. muck soil), then you are going to want to add some organic matter in the fall. This is commonly done by spreading leaves over the beds prior to covering them with straw. However, be warned that as Sandy eluded, weather will have a great deal of influence on the effectiveness. Adding large amounts of carbon heavy materials (i.e. leaves and straw) will lead to a nutrient drain when things really start decomposing in the spring. Be sure to either add a nitrogen source with your leaves now (for instance chicken manure, soy bean meal, etc.) AND some in the spring. As the microbes start to ingest the carbon materials, they will tie up oxygen, nitrogen and phosphorus. This makes them unavailable to plants in the spring. So, if you give them either a balanced application (C:N ratio of approx. 25:1) or provide them with a nitrogen source, you should be able to start in the spring earlier than with just leaves and straw.

2. Soil structure - simply adding this, that or the other to the soil will not improve the tilth over the winter. Neither will tilling, forking or double digging in the fall or the spring. The key to fighting compaction is patience and persistence. Patience: it will take two to three seasons to greatly improve heavily compacted soil. Persistence: it will take a great deal of physical labour, ammendments and crop management to improve that compacted soil. Be wary of anyone who has a one-application solution. For instance, you will often hear that adding organic matter will improve the tilth of clay soils. Yes, but it needs to be applied in such consistently high quantities that it almost becomes impractical. Further, some advocate adding sharp sand to clay. Again, working that much sand into clay soil would require such intensive physical work (either by hand or by machine) that it hardly seems worth it.

Regular applications of organic matter, regular working of the soil to get that OM down into the right layers, and regular growth of soil improving cover crops like rye, buckwheat, peas, etc., and after a few seasons you will see a large improvement.

Thanks to you both. Thats a ton of info!

Almost perfect guide for preparing garden for next spring already given.
Some of us may also be spending some time with their fall crops. My lettuce and arugulas are ready to be taken out and be transolanted at proper spacing.

It is also a time to transplant some perenials, if they are not fit to be where they are/were. I, myself transplanted laveneder, lemon verbena, lemon balm, stevias from my herbs garden to another location. I realized that they over crowded my small (about 50 sqr-ft) herbs garden.
Learning from my last year's experience, I will draw another plan, as what, how much/howmany/ where to plant.
Thinking about a cold frame also to get an early head start on seeds. Now I have time to build one.
And of course, I will be busy raking lots of leaves, mixing some with garden soil and making a compost pile of it. I hunt for earthworms too and give them home in my garden and compost pile. Their work is the most amazing to me, much better than micro organisms( I never see them !!) which are too slow for me.
I also mulch some plants with oak leaves to keep their roots warmer. Oak leave make a good winter mulch since they will not rot over winter and will work like insulator.