My Miata is put to bed for 5-6 months every year. The storage is indoor, unheated, concrete floor. My process is: (a) add an appropriate amount of fuel stabilizer (b) fill tank with top-grade fuel (c) fill tires to maximum allowed by tire manufacturer (d) drive for a few km to mix in the stabilizer and have the mixture reach the engine (e) remove anything of value from the vehicle (f) place in storage (g) remove the battery to be placed on charge at home every two months (h) install a dust cover. That's it. In the spring pop in the battery, deflate the tires to Mazda recommendation, and drive away. Nothing to do with storage, but it also gets an interior/exterior cleaning and a wax just before storage and if it rains on the day a wipe down before the cover goes on. I've been doing this with this Miata since the fall of 2011 and there have been no problems and none with the previous Miata either.
Just sayin'
Brian