Because the temperature will get cold enough to freeze a low-charged battery, you will need to remove the battery to a heated location
or insure that it is fully charged (hooked up to a battery tender at least monthly).
Sta-Bil or other gasoline stabiliser in a full tank is mandatory.
Be sure to run the engine to bring stabilized gas to the carb before final shut down.
Putting the scooter on the center stand is good, moving the scooter weekly to keep the tires round is good.
Running the engine is not necessary and if the temperature is -30, might be difficult to start the engine.
Keeping the scooter dry is good, but a cover may trap moisture under it if the cover is not made of breatheable material.
A waxing may be better than a cover. Many cover with an old sheet to keep the dust off.
Praying for an early Spring is useful. Shopping for safety clothing is also a good use of time.
Merry Christmas and Happy Scooting (in the Spring)