Get a battery tender and plug it in, otherwise, nothing else IMO. I don't drive my car hardly ever...to give you an idea when I went to start it the other day the battery was completely flat lol...luckily I have a hardcore jump starter so i let it idle for a few minutes and it was back to normal hahah
When I go on my holidays it's normally for about a month. I don't really do anything different other then make sure the doors are closed and the lights are off so it doesn't drain the bat.
I don't put anything in the gas tank (perserve the fuel) like some people might say, but in the last 5 yrs I have not had any problems after returning from holday,
I would just wash it really good and park in under the cover inside your garage.
BTW..My Cobra has sat since August 2007, and I just pulled it out June 21st, 2008. That thing ran great. I shifted at 7K and had people turning heads!!!