My 70 Duster has spent the last 5 winters or so outside.
Here is what i do.
Tarp it first with one of those actual car covers (dont forget to remove the antenna first, i forgot once) then put a another plastic typr tarp on top. Make sure they are extremely tight. If the wind blows the tarp around it will damage the paint.
Test your anti-freeze. 50/50 SHOULD be okay, 70/30 is the absolute max you want to go to, and you are running the risk of gelling.
Check your frost plugs. If the motor was rebuilt and restored, they may have painted the plugs in. If they are, you might want to pry them out and replace a few anyway. Then slap the person who painted them in.
As far as the fuel tank goes...this is a toss-up.. Drain the tank and you run the risk of the inside of the tank corroding. You could fill the tank all the way and add fuel stabilizer. However even fuel stabilizer isnt a perfect fix and the first tank in the spring is gonna be skunky. Both options kinda suck.
Put moth balls or those dryer sheets in your vents, under the seats ..frikken everywhere. Mice will love the chance to get into your car to make a winter home. I remember after bringing my car out one spring without doing this, i looked down and there was a mouse peeking out at me from the pass. side vent. Freaked me out.
If you can, put it on jack stands. Tires dont like sitting in the same place for months on end. Chances are you will lose air pressure too because of the drop in temperature and if it is buried in a snowbank..well you cant really tell until it is too late. (this happened to me too)
Take the battery out. This should be common sense. Charge it up and store it, but NOT on a concrete floor.
All i can think of right now. Hope some of this helps.
