I have 2 cars on long term storage in the province, here's what I am doing. Feel free to pick what suits you.

1. Disconnect battery and hooked up on a battery trickle charger/conditioner.
2. Dis-mounted tyres and placed wooden blocks underneath, position the blocks so that the suspension still bears the weight of the car, hanging the car with suspension in full droop is not a good idea .. (trust me on that one)
3. Clean the insides of the car, apply leather conditioner to leather trim, and leave moisture absorbent inside the cabin. (this prevents mildew/mould growth).. If you can, crushed charcoal in a shoebox will absorb odors too.
4. Clean the outside, underneath fenders, paintwork, apply wax if you want, then cover the car with a light car cover (indoor)
5. Make sure the fluids are topped off, engine oil, brake/clutch fluid, PW oil, tranny oil, etc. Get a full tank of gas as well.
6. If you can, have somebody start the car once every week or every two weeks. Just as so the engine and tranny internals are coated with oil, the electrics turned on and airconditioning checked. A 15 to 30 minute warm-up is okay.
7. Park the car in a clean place.. (no clutter/garbage present) .. A stationary car is an inviting place for rats .. who will make it their home, bring in some food, and chew on your wires too.
8. Leave your keys behind, and some cash for additional fuel.

These tips are not in order ... sorry! ..