Some items to check in addition to suggestions so far: Some of these things I sure wish I would have known back when I was getting mine.
-Check for rot/bad rust along frame rails under car.
-Verify VIN to ensure proper badging if RT
-Verify engine, a 383 looks just like a 440, small blocks look alike... etc, so check to make sure it is what they say it is.
-Check inside fenders and inside trunk and in and around headlight/grille area for evidence of major repairs to body.
-Check for broken grille and tail light parts and functioning hide-away headlights
-Check behind each wheel and around windshield and rear window for signs of body rust.
-Check front tires for signs of uneven wear that indicate suspension or alignment problem.
-Test drive car, of course, to verify everything works and it has power and that the car drives straight and smooth.
-Check for blue smoke when first starting engine up.
-Look at as many as possible to get a better idea if the one that you want is priced right.
Depending on your budget, you might not find a car with all of this stuff perfect, but you can get a better idea of how big of a project it is going to be and weigh each thing against what your abilities are when deciding what you want to "get yourself into".
I am sure others will post more, because there are so many things to watch out for with each different model of car etc.
Good luck... and trust nobody if they try to give you their word that something is what it is... cuz it usually isn't.
