Clear your plant beds of any debris and lay a cover crop to protect them over the winter months and provide soil sustenance until spring. You should also prune plants and shrubs which are seasonal and remove any weeds, or diseased greenery to prevent any spread.
Also, think about your garden irrigation system and limit any water waste by altering the timer so it runs at its least frequent setting. Rain sensors can also be installed which can delay the watering system following any rainfall.
It is ill-advised to shut down your irrigation system completely but if freezing weather is expected, then you may wish to turn off the main water valves and drain all connected pipes or hoses to avoid any damage.
It is also time to close and cover the swimming pool if you have one – removing any debris and equipment which will not be used before covering the pool entirely. You may also want to put the filter timer on a less frequent setting.