Re: How trade works
I usually type out a bill of trade giving the details of both items to be traded including descriptions, links to pictures, etc. Also full details of both parties with names, addresses, phone numbers, a copy of drivers licenses if possible. Signed, dated, faxed or emailed back and forth, etc.
I have also taken some other steps if I felt the risk was higher or the value was high where you can essentially purchase each others guitars through paypal, that does afford you at least a little more protection, but it obviously costs both parties the paypal fee.