Follow the advice about the RV antifreeze. Empty/bypass the hot water tank. Empty water from all holding tanks. Pump antifreeze thru all faucets, (don't forget outside shower). Put some into grey/black tanks. Do not put it in the fresh water holding tank, or hot water tank.
Do a thorough cleaning. Remove all food, soap, toothpaste, scented candles, old firewood, etc. It will attract rodents/bugs.
At night, turn inside lights on-plug any holes that you see light coming thru.
We do not cover our RVs. The best thing is to put it in a covered building-barn, garage, etc. , but that's best case scenario.
Do not leave any vents/windows open-moisture will get in and cause mold. Cover the tires, as UV damage happens in the winter, too.
Clean inside of fridge/freezer and leave the door cracked open.
Remove 9v/AA batteries from smoke detectors, as they will just go dead. Remove trailer battery and store inside.
Secure anything valuable to prevent theft. Put a hitch lock on it.
Check on it once in awhile, during the winter. When you check on it, be sure to say, 'Hi, We'll be hitting the road, soon'!