Start reading carburetor threads. If it's been sitting for 2+ years with gas in it, the carb is going to be really gunked up. Change the oil, gas, and dismantle/clean the carb and you'll most likely be ready to roll.
There's a thread over on ADV that swears that Pine Sol is a great degreaser/cleaner. I haven't tried it, but it sounds interesting.
As time allows, things like brake fluid, greasing the swingarm, tires, etc are all going to need attention as well.