Remove all personal items that might freeze and clean out refrigerators,
icemakers, coolers, and heads. Leave the doors propped open to these spaces to
Make sure hull plugs are out and the openings free of debris to insure that the hull does not fill with water over the winter. Clean exterior surfaces and wax if possible. Wash the bottom immediately after haul out while marine growth is still wet and easier to remove. Remember that most marine finishes are easily scratched, so do not use anything to clean them that you would not use on the hood of your new car!
The most important thing to do for your boat prior to winter storage is to cover it properly. Mooring covers and summer canvass simply don't cut it here. There are only three ways to do it right and they are: inside storage, having a custom canvass storage cover and frame made or to have your boat professionally shrink wrapped.
For most people, shrink wrap is the best choice between economy and protection. It is cheaper than inside storage or a custom canvass, and it fits tight so that it does not flap or flutter. This is the secret of shrink wrap's durability. A word of warning here: poly tarps which are available in most hardware stores, home centers and marine stores are absolutely useless as a boat cover, do not use them. While they are cheap, they very seldom stay on for the winter, and they shred, filling your boat with plastic debris and whipping against your boat's finish as they flutter in the wind, while their brass grommets are damaging your finish.
If you want to do the work yourself, and plan to keep your boat for many years, the custom made cover may be your best choice. Beware, they are extremely heavy and must be used over a very well made frame for durability. You must be willing to make a large initial investment to buy the cover and frame materials, and plan to spend the better part of a day or more to erect and remove these covers.
Make sure your cover is ventilated. There are plastic vents for shrink wrap and canvass, although canvas vents somewhat through the material. With shrink wrap it is imperative that ventilation is provided to prevent mold and mildew. Proper venting will prevent this from happening.
Whatever choice you make, make sure your boat is covered. More damage is done to boats by exposure to weather than anything else. Interiors are aged, floors are rotted, and gel coat faded before its time. Covering your boat during storage protects your resale value and assures you that your boat will be ready to go in the spring when you are.