Here is my quick list:
1. Drain cockpit shower. I drain from under galley sink and I now remove the compression elbow fitting behind the cockpit shower that has frozen and broken a few times.
2. Antifreeze raw water washdown system. Don't forget to ensure there is antifreeze in the pump/strainer and ensure there is antifreeze in the metal part of the thru hull shut off valve just above the shut off handle. You can drain the system if you want, but there ARE low points that will hold water in the system including the strainer, the connection at the bow in the anchor locker, and the hoses.
3. Low-watt heater/fan in the engine room and in the galley; cabinet and head doors open.
4. Insulation for engine room vents on standby.
Anyone have any other must-do items?