Winter is setting in; what should I do to store my car for the long haul?

Assuming that you are in an area where the car will be put up for three or four months there are several things I would recommend.  Add a fuel stabilizer to the gas tank, top up all the fluids, check the coolant levels and add antifreeze as required.  Protect the interior with moth balls or other pest deterrent products.  This applies to the trunk and engine bay as well.

How about the storage site; anything special?

If it's in your garage a car cover is always a good idea. If the floors are painted put some cardboard under the tires to prevent the paint from lifting. Place newspaper, plastic or cardboard under the engine and transmission area to catch oil drips (it's a British car after all). A sheet of plastic also works well to protect the floor with an added benefit that it helps to isolate moisture from the underside of the car.

Should I try to start or run the car periodically?

This is always a good idea, especially if you have ready access to your car. Take precautions to properly ventilate the area while the car is running. Move the car forward and back a few feet to check brakes, clutch and drive line. After running the car for twenty minutes or so check the engine bay and under the car for oil, hydraulic or water leaks. If the car is off site make a plan to make cursory visits to check on overall condition and when possible start and run it for a short time.

How about paint, fabrics and rubber products; anything I should do ahead of time?

Wash and wax the car prior to storage and make sure it is completely dry before you put it away. Next, vacuum out the interior and trunk. Remove anything that attracts mice, squirrels or other pests. Again, here is where a car cover is valuable. Not only does it protect the paint but the cloth tops and interiors as well. You can pre-treat tires with a number of commercial preparations and this is a good idea. Moving the car a few feet will prevent flat spots and sidewall cracking.