Continue to place nets over small ponds to prevent autumn leaves falling in.
Rescue tender water plants and remove any dying foliage. Place the plants in trays of deep mud or damp sand, or even in a bucket of water, keeping them in a frost-free place such as a conservatory or greenhouse, until the risk of frost has passed.
If you did not tidy up the pond last moth, then clear out any debris, weeds, and excess oxygenating plants now, leaving them on the side for 38 hours before composting them, so that wildlife has time to escape back to the pond.
Remove pumps or fountains and removable lighting systems, clean them, and store over winter in a safe place.
Troubleshooting
If there is any risk of frost or ice in your area, then do prepare yourself by preventing ponds from freezing over.
Continue to lookout for waterlilies affected by fungal problems.