If you have oriental bittersweet or Japanese knotweed growing on your property, you should cut it down, remove and bag all parts as soon as possible as the plants are probably covered with berries or seeds which will be spread by birds and the wind. These very invasive plants will probably grow back from their roots, but at least you will not have many seedlings sprouting in other corners of your yard next spring. To totally get rid of these invasive plants you will need to repeatedly cut them down next year and sometimes for several years. In the case of Japanese knotweed you should bag and dispose of all parts of the plant as they easily root and grow again.
Fall is a good time to divide and replant perennials such as daylily, iris, hosta and bee balm. Black-eyed Susans, garden phlox ad tall sedums can be divided after they have finished blooming. Fall is also a good time to plant shrubs and trees. The cooler weather and usually moister soil stress the plants less and allow them to take hold and grow.
Speaking of cooler weather, it is not too late to plant lettuce, spinach and radish. They will do well in the cool weather.
If you grow Siberian iris cut the leaves down to 4-6 inches tall. I find that voles and chipmunks will hide under the long leaves over the winter and eat the crowns of the plants. In the spring you will not have any plants left under the leaves. Cutting the leaves shorter in the fall removes the hiding places.
You can save yourself some time and nourish your lawn by not raking your lawn. Instead mow the leaves to chop them up and let the bits of leaves decompose. This will work with oak leaves and a thicker layer of leaves if you mow twice to ensure that they are chopped up small enough.
Leave the seed heads of your cone flowers and black-eyed Susans standing in your garden rather than cutting all down. They will feed the birds this winter and add interest to your winter view.
If you had any disease in your tomato plants or other vegetables be sure to clean up all leaves from the ground as well as the plants themselves and dispose of them in the trash. Do not add any diseased or infected plant parts to your compost as they will cause the same problems next year. Try to leave your garden soil as clean as possible before winter. The cold does not kill many of the pathogens that affect your plants. It is a good idea to remove and dispose of any weeds as well to reduce their seeds.