keep gas tank full to keep it lubed and prevent rust incase of heavy rain. check all fluids for that reason. If you aren't going to drive it, put the car on stands, this way, tires don't "set" like theotherdave has told you, also, you don't want warped rotors, pads, etc...because of rain. Keep it up several inches with 4 jackstands and you will be good to go !!!