When I first became interested in folding cameras, someone gave me a link to this article:
I found it very helpful and it got me started on the road to a string of folders purchased over the next few years. I still pick up a folding 6X6 or 6X9 and take it out once in a while.
Find a nice folding camera, preferrably with a coupled rangefinder. I have a very nice folding Mamiya Auto6. It's heavy for the genre, but it's got a great lens, a unique but superb focus system (the film plane moves back and forth controlled by the coupled range finder mechanism) and is very accurate focus.