I've stored some cars outside, not a Fiero yet thankfully.
As for rust dont store it on concrete or pavement. Dirt or even grass is fine. The paved surfaces sweat moisture up onto the car. One could put barriers under the car, but I have not done that outside, only indoor cold storage, I used layers of cardboard. Outside maybe a rubber mat would work, but rodents might like to chew it.
You could block it up higher off the ground as well.
A major concern could be rodents. Various tricks exist to keep them out of the car. make sure the car has nothing that they like, no old french fries under the seat for example.
An easy one is just add a ton of dryer sheets all over inside cabin, trunk, underhood, in exhaust exits, around engine bay, they seem to not like the smell of them.
Put Stabil in the gas and fill the tank with mid grade octane no ethanol if you can, (it takes longer to spoil).
Disconnect the battery (I bring mine inside to store warm).
A car cover that fits well and is made for the elements, but Id say not a plastic tarp, they trap moisture which will get excessive when temps rise after being cold, and if a cover moves in the wind it can damage paint by abrasion.
The oil spray is a good idea. On my daily driver Saturn, and my pickup which is always outside I spray most of the underside with CorrosionX.http://www.corrosionx.com/corrosionx.html
We are assuming you are in Canada so it will be cold.
[This message has been edited by 2.5 (edited 12-30-2013).]