Rules are pretty simple. You just post here whenever you have a good or a bad trade, and let us know how it went. Please post as much relevant information as possible, else you probably won't be taken seriously.
For members wanting to check out a user's feedback, please read more than just the title of the thread. You may see several threads stating "SoandSo's a scammer, I have proof!" and let that scare you away. Just read the thread(s) pertaining to the person you want to trade with. Perhaps the original poster is just harrassing a good trader. Look at the proof provided, read the replies, make your own decision.