I use these Schumaker trickle chargers. They work great. I (in my humble, worthless, internet attacked opinion) believe that the battery is the only real major issue.
Amazon.com: Schumacher SC1319 1.5A 6V/12V Fully Automatic Battery Maintainer: Gateway
You can put in StaBil gas stabilizer if you have a full tank of gas, but if you leave it with a small amount of gas in the tank, then you can go get a full tank of fresh gas when you get back.