Bitcoin Forum

If you want to trade unlisted coins, what is the best procedure to do so? Is there any guide for that?

There's not really a guide required for that... Just do this:

1. Is the stranger on Bitcointalk/Discord trusted?
[Yes] -> Go to {2}
[No] -> Go to {3}
2. Ask him how it works and he should be able to guide you through it. For all safety, you could tell him you're recording it and if you say that, you should do it as well.
3. Contact a reliable escrow. (On this forum or something like Bitify)
4. Trade.

If you come across any problems, just specify what you need help on exactly. You can PM me with your problems too, if you want.

To safety trade to someone unknown or strangers to be safe only trusted escrow can help you to trade to anyone not trusted
Here is the list of trusted escrow and hope it can help you to deal to someone https://bitcointalk.org/index.php?topic=855778.0

How do I find or contact one?

Both participants would then send their coins to the escrow and after he received it from both parties, he would forward them? Is it a common practice that he get a fee?

This is what I was searching for. Thank you all