You live where it freezes? I'd get fuel conditioner then.
Otherwise starting it up once an awhile is good. Make sure you let it run long enough to warm up and idle smoothly. The worst thing you can do is start it up and not let it get to normal operating temperatures.
I'm sure the stuff my motorcycle manual says to do for storage has good reason and can probably apply here too:
1) get off ground, tires gets soft spot after awhile if not moved.
2) fuel conditioner if not run for several months
3) take battery out and put it on a trickle charger
4) leave at least 3/4th tank of fuel, do not leave empty.
Basically, what stingray said

Errr, I like this new " Warning - while you were typing a new reply has been posted. You may wish to review your post."
Also what chasmosis said
