2005 Undriven/Garaged... how to get running??

Hello,
We have a 2005 Cadillac Deville that was purchased and for the most part undriven (less than 800 miles currently) It has been garaged the entire time. I am trying to get this thing back on the road now...

Here is what I am assuming needs to be done:
A new battery (I know it needs this)
Drain out the gas (would this be simply siphoning the tank or would I need to do more?)

Also:
Would it need new belts/tires? Or anything else I need to consider?

Thanks,
Evan

No one can really tell you specifics, look at the tires see if they have cracks in the tread or side wall, the oil and filter should be changed, you will not be able to siphon the gas on this car, if there is less than 1/2 tank fill it up with fresh gas, then try to start it. It should have all the systems and fluids from the ground up checked by a pro, also look for animal infestation.