i wouldn't leave the fuel tank low. They condensant so get water in them, although a good tank full of fuel won't be affected much i suppose by the small amount of water.

As someone said, pump the tyres up or even put it on axle stands, That way you won't cause flat spots on the tyres.

My concern with not running it would be that the valve stem seals may dry out if you get some oil flowing over them. Dunno just a thought. Don't just start it for 5 mins either. You get condensation in you breather and end up with a blocked gunky breather system.