A lot of people are glad to get a good looking, quality car that has been parked somewhere for several months but they seldom know how to wake that car up. The worse thing someone can do with a car that they picked up out of someone's yard is charge the battery and hit the starter.

IMO, a car should really be preped before you try to start it. I would recommend the following:

1. Have the car towed home or where you can do some work on it.
2. Drain all the fuel out of the car. Hooking something up to the fuel rail and turning the fuel pump on to pump the old gas out might be the best direction. Maybe jump the fuel pump, but don't try to start it and dump that old BAD fuel through the injectors and motor. From what I have read, if a car is parked without a fuel stabilizer added will allow the gas to turn into terpentine or something.
3. Drain and change the oil and filter. You don't want to pump that old nasty oil through the motor.
4. If the car has been sitting longer than 6 months, change the fuel filter and air filters. You really don't want to hit the starter and risk blowing deteriorated filter particles though the system. Also, if critters (mice, etc.) have made their way into the intake or air box, you don't want to suck their nest into the intake.
5. Bleed the brakes, and maybe even flush the brake system with new fluid.
6. Change the antifreeze/coolant.
7. Check the belts for cracks, change any that needs it, including the timing belt.
8. If you don't know the age of the timing belt, replace it with the rollers (especially if the car has been sitting over 12 months).
9. Install a new battery if the one in the car is over 24 months old.
10. Turn the car over by hand twice after you change fluids.
11. Then try to start the car.

I know how exciting it can be to get your hands on an old car that you are hopefully getting a deal on (if not free), but you really should protect your new jewel by taking the above precausions.

If anyone has more tips or information that should be noted, please add it in this thread.