It is also okay to string a pet plant along, if you're inclined. If you have a full fridge and can't deal with processing the last picking of green beans, or if the forecast has a rogue hot spell after one cold night and you think you might get a few more jalapenos, go for it. Cover plants with remay, sheets, or tarps, and most things can survive the first couple of light frosts. My summer squash is miraculously healthy and plugging away at fruit (and I'm not tired of them yet!) and I think I"ll let that baby drag on until the final freeze.
Don't try to do everything at once. Just like in the spring, tackle a section or two at a time. I picked most of the remaining harvest last week, and tackled the aformentioned tomato vines; this afternoon I'm working on peppers and beans. Prioritize by what is the least cold hardy (BASIL) and what can stay standing long into winter (kale, broccoli, leeks).
Don't leave everything until next spring either! Leaving mildewy or diseased plants over the winter is just creating issues for the following season. Non-beneficial insects will overwinter there as well. Besides, cleanup and preparation makes getting started in the spring SO MUCH easier. Everybody hates weeding, especially with the rationale that the coming freeze will kill plants anyway, but a last pass in your gardens and paths will really pay dividends later on.
It's okay to not compost everything. Our city collects yard waste, and while I try and recycle most of my weeds and garden byproducts within my own property, some things just aren't worth it (for me). I send sickly tomato and potato vines to the curb for pickup, as well as woody stems and root balls that will have a hard time breaking down. This reduces the time it takes my compost to be ready to use, and also cuts back on introducing disease or weeds. While definitely having volunteers like dill or celery is the norm in my garden, unfriendlies such as stinging nettle are not welcome. Even plants I like that are aggressive (cleome!) will often get send to the city, whose composting volume is large and hot enough that they do a better job of killing seeds and fully composting woody stuff.
If you don't have this option but you have the space you might want to separate out the more difficult waste products and give them their own pile. As woodier bits break down you can introduce them to a future turn of the compost.
Speaking of which, fall is a great time to turn that big pile of compost. I mostly feed my beds in the fall. One reason for me is that I have chicken manure going into my bins, and depending on the timing or my skill at building a great compost pile--this may not be broken down thoroughly when it goes into my garden. Too-fresh manure can burn plants, and has the potential to transmit pathogens. While I don't have a lot of worries about catching anything nasty from my girls, the generally accepted practice is to wait 90 days after spreading fresh manure before harvesting (longer if the food is in contact with the soil). So for us Northern gardeners, this works out well for feeding beds in the fall anyway. If my compost isn't fully finished, a last sit in the garden over the winter helps break the remainder down, all the while sending nutrients into the soil below.
Putting gardens to bed: The last fall task for me is mulching with leaves and grass clippings. The final mows of the season are great for creating a lovely brown/green mix of mulch that can cover sleeping gardens and feed them all winter long, as well as protecting the soil from harsh conditions. If you're a planner and know where your earliest crops will be next season (onions, lettuces, peas etc) you can prep those beds thoroughly now, so they are ready to plant as soon as the ground is warm enough. No digging required, I often plant my onions right through the mulch. Actually the first planting will be this fall's garlic: so I clean up and feed that bed first so I can plant around Halloween, and mulch it super well with leaves/grass (and straw, if I have it).
Makes notes for next year. I definitely struggle with this,but it's the perfect time to reflect on what worked and what didn't, and what your goals are for next season. I think the hardest part of this is the natural let-down of the end of the season. As I work in my overgrown and weedy beds, I tend to only see the failures (how did I make so little pesto this year? Why were my peppers so non-prolific?) but sitting down with your spring notes/plans can help you gain a little perspective and remind you of what did work (what a great year for cauliflower, I had almost forgotten).
While most of this week I have just wished for it all to be done already, making plans to spend the last brisk sunny days putting my garden to bed for the winter is not the worse chore I can imagine. I can't wait to see the (mostly) neat beds ready to sleep away until spring.