Ray Zee's comment about running it is good advice. If you don't/can't run it, be sure to pull the plugs and spray the cylinders with oil to keep them from rusting and seizing. And the gas tank and lines have to be drained.

There are probably another dozen things you should do, but that's all I remember. And I learned the hard way. I drove a '79 Monte Carlo into a garage without doing anything to it. Just turned it off and walked away. Three years later when I thought I might try and get it back in working order I learned all the bad news. Wound up scrapping it.