Grant, I think you already said the most obvious is to use common sense. I always talk to someone over the phone first. Ask them questions about what you want to buy, their motivation for buying and selling etc. if you get a bad feeling or it seems fishy walk away. I acknowledge I have a CHL up front. That way regardless if I am buying or selling, the other party knows there is a good chance I am armed. Plus it lets a seller know you can pass a background check. If you end up meeting, examine everything to make sure it matches the description. If there are too many people there and you are uncomfortable, just leave. Even if you get this far you can still say no thank you and walk away. Use an open trunk or something to examine anything and obviously don't hold it up and waive it around. If you want to function test first ask to meet at a range. Bring your own gear and ammo. My expieriences have been about 50/50.