[oem4me]

First and foremost is be patient and do not let emotion get in the way of judgement. Next, know that a sellers honest take on their truck may be way different than yours, so you cannot rely on a verbal description only.
Then, ask lots of questions and insist on photos. Ask for pics of the ugly stuff, specifically. Any seller reluctant to provide shots of the worst aspects, however minor, is hiding things. What I say exactly is: "Save us both time and show me the flaws that I would be looking for if I was there in person".
Lastly, If you make a deal on the phone, do it contingent upon inspection by yourself or a known reliable third party. This last one can cost a few bucks, but the price of a plane ticket is cheap compared to getting stuck with a vehicle you wish you didn't own. Trust me ... I know.