After the first frosts hit you should spread mulch at the base of tender plants.
Drain everything in your garden of water that might be damaged by sudden frosts.
Summer plants should be deadheaded this month, also continue feeding summer bedding up until the first frosts.
It is December! Snow and frost are more common! For tips and tricks on gardening in December check: bit.ly/GardenDecember
Outdoor containers should now be insulated from frost: you could try bubblewrap!
Is there already any risk of frost in your area? Do not forget to prevent your pond from freezing over!