If you are not fortunate enough to find yourself in a place where you can rid the winter like 530ktm and myself you might have to winterize. I had jetski's and even in SoCal they got put to bed for the winter. The first thing is the fuel. Stabilizer works, but make sure to run the bike some so it gets in the carb bowl as well. I liked to completely drain everything. Completely means the carb too. It's just a screw and is rather easy.
If your bike is so equipped, don't just leave the battery there all winter. It will be dead for sure come spring. Use a batter tender or better yet take the battery out and store in a heated area. Again use a tender or charge it once a month.
That said, I prefer my winterizing plan. Ride!