Since gasoline now includes ethanol I would add stabilizer and Star Tron Gasoline Additive. You can buy them at a marine store such as West Marine.
Be sure to fill the gas tank to reduce condensation. A battery tender is a good idea as well.
http://www.starbrite.com/productdeta...Startron%20Gas
http://www.starbrite.com/whatsnew/ST...%20p3072D2.pdf