Although I'm lucky enough to be in California where the temps don't fluctuate a lot, I do store my scooter when it's too cold for me to ride.
I usually fully charge the scooter, fold it down, and put it on top of a crate/sturdy box to keep the wheels off the ground (to retain the shape/quality of the tires) and throw a flat of cardboard underneath.
Be sure to check your device's battery regularly if you have a key-start ignition, immobilizing alarm, or other components that can slowly drain the battery. If kept in storage for a long enough period of time, the battery can get so low that it will no longer be able to hold a charge.
Any storage tips or tricks that you have?