comes to having a prepurchase inspection down (first thing to do if you can agree on a price), personally inspecting it yourself before closing the deal and having a round trip ticket.
I'd also recommend having a purchase and sale agreement in hand before you buy your plane tickets. When I did a long distance deal I also agreed to pay a small deposit after I received the certificate of title in the mail. The exchange of title and deposit assures the parties that they are dealing with someone serious about making the transaction, although I stipulated that the deposit be refunded if I showed up and decided not to buy. All this is time consuming but helps insure that you will get a decent car and are dealing with someone that is serious and probably honest.
