This may give you some pointers:

http://www.ehow.com/how_14375_prepare-car-long.html

I googled for +"long term storage" +car

A google search for 'laying up car' brings up many sites - the first two
being:
http://www.rac.co.uk/web/carcare/advice/general_help/laying_up_a_car

http://www.aa.co.nz/Section?Action=View&Section_id=82&Story_id=1658

The message <4R%wf.730$h_.402@fe11.lga>
from "eBob.com" <fakename@totallybogus.com> contains these words:

You don't say how long.

Don't worry about the cold - cars survive cold all the time and as long
as your antifreeze is up to strength you'll be OK. I'd empty the washer
bottles though - not 'cos they freeze but 'cos they grow slime which
blocks the squirters.

Leave the handbrake off. They have a habit of seizing on if left for ages.

Consider a battery charger. Not the sort for charging batteries but the
sort that maintains a steady charge during periods of disuse. The
classic car people use 'em all the time. Keeps the battery charged
without overcharging it. There's an article about them here
http://www.autoexpress.co.uk/product_test/59293/battery_conditioners.html
and I'm sure such things are available in the US.

Other than that, as long as you're not away for several months I
wouldn't bother standing it up on bricks to relieve the tyres, I've had
cars stand for six months without tyre problems.

Rust isn't usually a problem with Audis, but try to put the car away
when it's dry and arrange to have some ventilation.

Finally - petrol ages and can make it hard to start a car when it's gone
stale. You can get fuel stabilisers from marine shops, outboards are
prone to this 'cos people only use them for a few months a year. You'll
need to put it in a few miles before you park up or it won't have got
through the pipes. Alternatively just store it with the tank very nearly
empty and fill up when you get back.