Hi Micah and welcome to TMF.
Where to start, well first thing is budget, then you are looking for the best car you can get for your money. Steer clear of modified cars as this will help to keep your insurance down. Look for 998's as these tend to be cheaper overall to insure.
Condition and rust is everything and leads to the most heartache and hard work. So looking for a car with minimum rust is essential. Unless of course you can weld or have a family member who can.
Mechanically the carb cars are simple to maintain and easier to fix from an engine point of view.
There are lots of other things but what you are looking at is a very basic mechanical car which is ideal for learning how to maintain and of course modify.
Ebay, Gumtree are good starting points. We do have a classified section on here as well so worth perusing.