It beats bad stuff happening... 

These are the steps I follow, in order, to winterize our trailer.  

• Wash and wax outside of trailer
• Park the trailer on boards and chock wheels
  
• Inflate tires to 125% (62.5 lbs in my case, as instructed on the Goodyear site)
• Fully drain fresh water tank, black tank and gray tank (use the Tornado tank rinser on the black, rinse out the gray until all sensors clean)
  
• Open drain valves under trailer and drain water system (open kitchen, bathroom, outside taps to let air in)
• Using hand pump, attach to outside city water inlet, insert suction tube into RV antifreeze jug and pump into inlet
• Pull anode from hot water tank and let tank drain fully; check anode and replace if necessary
• Remove clothing, linens, towels from all storage spaces
• Remove all food from cupboards and fridge
• Move flashlights, candles, power supplies to basement
• Vacuum trailer fully, including food cupboards
• Wipe down inside of cupboards with damp cloth or spray cleaner
  
• Defrost and clean inside of fridge and freezer (leave doors propped open for the winter)
  
• Clean stove, oven, microwave
• Remove all items from bathroom including the vanity and under the sink
• Cover power jack with plastic bucket
  
• Close fresh water, black and gray tanks, and drain valves under trailer
• Put RV antifreeze in the water lines (not the hot water tank or fresh water tank):
  
• turn petcocks to winterizing position (there are two at the pump, three at the hot water tank)
• insert pump intake hose into jug of red non-toxic RV antifreeze
• turn on pump (it will run for a bit while the lines get loaded up)
• run the following taps until antifreeze appears, running long enough to get antifreeze into traps:
• kitchen hot and cold
• bathroom hot and cold
• toilet
• shower hot and cold
• outside taps, hot and cold
• Place scented bounce sheets on each bed, couch, kitchen table, counter top, under kitchen sink, bathroom, in food cupboards, and in dish/utensil cupboards
  
• leave all cupboard doors open slightly for air circulation
• leave both roof vents open slightly for air circulation
  
• Turn off propane tanks
• Install cover on air conditioner
• Install cover on Hensley Arrow
• Install tire covers
• Tilt trailer for runoff

• Remove battery from tongue; clean, charge up and store both batteries in basement