With day light hours getting shorter your waterlily pads are getting smaller leaves and not flowering as much. Stop feeding them and if they are hardy lilies then move them to the bottom of the pond to overwinter.
The same applies for other potted hardy plants be sure to cut them back so the vegetation does not freeze and start decomposing in the water.. Tropical blog plants can be potted and brought indoors for the winter.
As your floating plants start to shrink in size more and more of your pond becomes exposed to birds and other predictors looking for some fresh fish. Make sure you have shelves or caves for the fish to get into or under to avoid these attacks. A large clay tile works great.
When the water temperature reaches 60 degrees it is time to slow down on feeding your fish. Being cold blooded as the temperature drops it slows their metabolism and they digest the food much more slowly. I recommend no more than twice a week. When the water temperature hits 50 degrees stop feeding all together.
Now is the time to clean out the pond a complete cleaning is best. If that is not possible than remove all the twigs, leaves,and dying vegetation and vacuum every thing. Then place leaf netting over the pond and clean it daily. Skimmers are not made to get all the leaves only some now and then it would quickly clog and stop working.Some people build a frame over their pond to hang the netting on.
If you take care of these chores this fall your fish should survive the winter just fine and be healthy and happy next spring.