Because we do not have any lasting freezing temperatures, you do not have to worry about the expansion of ice. Therefore, you do not need to drain your freshwater tanks, or add antifreeze or blowout the lines to the boat's plumbing. I do recommend that you pump out your holding tanks and add in an odor treatment product.
One of the biggest culprits is mold, and mold loves to grow in dark, damp areas. Therefore, PFDs, wet towels, swim fins, bedding and cushions, basically anything that might grow mold, should be taken off your boat if you do not plan to use your boat. Open all the cabinets and shower doors to allow air circulation and hang dry towels over the tops of the doors to keep them open.
Electric dehumidifiers work well if your boat has shore power, or you can use the dry chemical dehumidifiers, but you will have to empty the containers once in a while.
Now, check the water levels in your batteries and replace the waterpump impellers. To top off or not to top off your fuel tanks is the question, whether 'tis nobler to suffer water condensation in the tanks or stale fuel. I will write more on this topic in an upcoming column; however, fuel docks will have a fuel stabilizer that you can add to see you through to the the beginning of next boating season. Also, I recommend that you empty and dry out any portable fuel tanks. The fuel docks in the harbors can help you to dispose of the fuel properly and safely.