What do you think? Best outside car storage for this winter

When there are no other choices but to store a car outside during a northern winter, what do you guys think is the most effective way to do it? (Without portable garages, new buildings, etc.).:dontknow:

Tarp on the ground first, then a tarp over? Then wrap it up?

What do you think?

I gotta do it, but want to be smart as I can. Rog