My first two years of storage I jacked it up just enough so the weight was off the tires, but not so much that the tires were off the ground.
This year I'm going to jack it up and take off the wheels entirely. Primarily because I'm getting them bent back into shape during the winter and will be too lazy to put them back on.
Only things you really need to do for long-term is disconnect the battery and make sure you have a full tank of gas (avoid moisture condensation). You can put in stabilizer if you want, but only carburated engines really need it. Fuel injected engines don't have much for varnish to form on. My motorcycle on the other hand gets the full stabilizer treatment. The carb bowls in that thing attracts varnish like a magnet.
My friend had his 89 Firebird (barely fuel injected) stored for three years. He didn't do anything to prepare it. After installing a new battery and new tires it started right up with 3 year old gas in it. Other than battery drain, fuel injected vehicles really don't get affected by long storage periods.