make sure the shutter fires, the optics aren't foggy, the lens doesn't have any scratches or fungus, and battery contacts are clean and not corroded.
I'm a big fan of 60's-80's film cameras and there is always a certain risk buying cameras that old. in most cases you are going to have to replace light seals and mirror bumpers (on slr's) and the first roll of film you run through and develop is always a test. until you get some pictures back, you won't know if the meter is accurate, if the shutter is firing at the same speed you set (mechanical shutters run slower as they age), and if it is leaking any light and fogging the film.
as far as recommendations go, everyone you ask will something different. personally i'm a fan of minolta and i think the srt cameras (101/201/etc) are very well made mechanical cameras with an accurate meter and have excellent glass available relatively inexpensively.