Do
- Check condition by asking for pictures. If pictures are taken from afar, generally be suspicious because such pictures can be easily doctored, or totally miss a detailed flaw.
- Always buy locally, and always meet in a public place. Sometimes going to someone's house is alright, but it's much more dangerous than meeting publicly.
- When meeting publicly, always bring a buddy or two along.
- When meeting publicly, arrange a signal to know when you've seen the dealer, or your customer.
- Always do a check over the condition of the item in question before you hand payment over.
Don't
- Accept or give anything but cash. The danger of being ripped off increases by leaps and bounds if anything else changes hands.
- Be afraid to back out of the deal if anything seems fishy, or the item in question isn't up to par.