This isn't a "how to" do each step (you can ask that later).
Are you storing indoors or outdoors? Near your house, far away and won't even see it daily? Temperature controlled or not? Covered by a roof or RV cover? Or no cover? What are the winter temps in your area? Snow/rain/heavy winds/ice possible?
1. Remove all water: drain freshwater tank, drain water heater.
2. Drain gray and blackwater tanks.
3. RV antifreeze (bypass water heater), hopefully your RV has a valve to siphon the RV antifreeze using the RV's water pump to pull the antifreeze to each fixture (all faucets and toilets, showers)
4. Empty refrigerator, leave door open.
That's the bare minimum. Other owners will jump in and add stuff - but that prevents water from freezing and damaging the RV plumbing and/or water heater.
2012 FunFinder X 210UDS
4-68 watt flexible panels; 1-215 glass panel/4 Battle Born LiFePO4 Deep Cycle Batteries
2014 Ford F350 6.7 Liter PowerStroke V-8 Diesel longbed, SRW