Clear the leaves
Leaves left in the pond rot through winter and use up oxygen. Remove them before freezing weather or cover the pond with a net in fall.
Fish in cold water
Fish slow down in cold water. Stop feeding when it falls into the low fifties and keep it off until it warms. Deep water gives them a stable place to rest.
Keep a hole open
A small pump or aerator keeps a hole in the ice for gas exchange. Never smash ice, because the shock can hurt fish.
Plants
Cut back hardy plants after they die back. Move tropical plants indoors. Sink hardy lilies to the deeper shelf.
Equipment
Disconnect and store submersible pumps if you shut down the waterfall. Drain exposed pipes. Fountains and bubblers should be drained.
Watch the level
Evaporation continues in winter. Check the water level and top up if needed so the pump does not run dry.
Keep leaves out, keep a hole in the ice and stop feeding when the water cools.
