When storing a refrigerator or freezer, there aren’t dozens of rules but the rules that do apply are critical to follow. To move a refrigerator or freezer properly read Moving Refrigerators and Freezers.
First of all, before placing a refrigerator or freezer into storage take the door off and put the hardware back in the appliance or in a marked bag taped to the inside of the door. This is for safety and for air flow to prevent mold and mildew. You can prop the door open (with a piece of wood, etc) but if pressure is put on the seal, the dents made can remain permanent ruining the seal and the efficiency of the appliance. If you can’t take the door off, clean and disinfect the inside and seal of the refrigerator or freezer (which you should do anyway) and use something like a long piece of cardboard to prop the door open. You can use desiccant pouches or other silica type products or baking soda to remove moisture from the inside of the appliance while in storage.
If you can store the refrigerator or freezer on a skid for additional air flow do it and wrap the appliance with a tarp or some shrink-wrap.
While in storage some refrigerators or freezers suggest to plug-in and run the unit every couple of months for a couple of hours to ensure proper lubrication of the compressor.
While in storage make sure that your refrigerator or freezer is left on its feet and not tipped or stored on its side as this will damage the compressor. Also, when reinstalling for use, let the refrigerator or freezer sit for 24 hours to let any refrigerant from evacuating the compressor. This is critical to follow to ensure proper operation of the refrigerator or freezer.
When removing from storage, before restarting your refrigerator or freezer vacuum or clean all coils and vents to ensure proper air flow.
One last tip for storing refrigerators or freezers tape the cord up to the back of the appliance. I have seen many a cord get pinched and ripped off by getting caught between the appliance and the floor or the dolly and the appliance. Follow these tips and your refrigerator storage (or freezer storage) should be successful.