1. Meet in a neutral place. A gunshop or range. Inspect the hell outa the piece you are getting. Don't trade and go.
2. Make sure before you do to trade that you have contact numbers, pager/cell, and that you and the other party has nailed down what is expected.
3. Be prepared to exchange info, address, Driver's licence number, ect. Not everyone does that, but I have the past, just to keep some sort of record in case a problem arises. Most often I don't unless I get a vibe off of the other person.
4. Take your time...don't rush into the trade and don't feel like you should complete the trade if you don't like what you see.
5. Take a friend. Gives you a piece of mind and a witness. In todays world, I trust NO ONE, but my closest friends.
6. Got any recipets? take them to show proof of any claims you made to the other party when working out the deal.
These are just a few of my self-imposed guidelines...