Sad day, but I had to put the car away.

Fill tanks, add StaBil.
Park it/them in the back of the shed/shop.
Check coolant (freeze level).
Jack it/them up, put on jackstands.
Disconnect battery (from vehicle), connect battery "tender".
(I have trucks, but if I had a car I'd add, "Install cover").
Start every month and let 'em run for 30 minutes or so.

And that's about it, really.