Most of this has already been said but
Don't leave the handbrake on if its safe not to do so
Over inflate the tyres by just a few PSI, if you cant drive the car at least roll it back a few feet every few weeks (helps avoid flat spots)
Connect a trickle charger if you have one
Throw a few of them moisture absorbers inside
Drive the car now and again and get it up to temp, Try and avoid just leaving the car ticking over in the car port for extended periods.
A friend of mine goes through the hassle of placing his car on axle stands ( I cant see any benefits to this though)
Lift up the windscreen wipers
Before you start driving it in the new year change the oil and filter and fill the tank full of fresh fuel