Six years is a long time for a car to sit, especially if it's out in the elements. I'm curious, did you park it with a full tank of gas, or was it empty? Either way you're gonna want to drain the old gas out of the tank. But if it was empty there is a good chance that you have a layer of rust on the interior walls of the tank from condensation. It sounds like you are already planning to look in the tank. Hopefully the baffles are still intact.
Before trying to start it, I would drain and replace all fluids... oil (replace oil filter), trans fluid, coolant, power steering fluid, brake fluid, clutch fluid. Be sure to bleed your brakes, clutch, and coolant after refilling. Then I would also use a breaker bar and rotate the engine by hand (counter-clockwise only), to make sure it will turn freely. Do this while you have the spark plugs out to make it easier to rotate.
It's likely that one or more of your brake calipers will be seized. If so, you will have to take them apart and clean them, but you should be able to get them to work again. Unless you just want to replace them. The brake rotors will also have rust on them. Depending on how much moisture they were exposed to, you may want to remove them and clean them up a little with some emery cloth.
Make sure all your tires are up. I would also replace the spark plugs, distributor cap, rotor, and air filter. A new fuel filter would also be a good idea, but I would wait until after initial start-up. There will be crud that comes through the fuel lines at first, and you don't want to plug up a new filter.
Good luck and keep us posted. And definitely add some pics.