Tips for successful trading:
If the person you've sent a trade request to declines the invitation, avoid harassing them by not sending them more trade requests.
Avoid scams by not letting other players, even your own friends, borrow your item, unless you don't care about not having it back.
ALWAYS think a trade through before you accept. If you're unsure about a trade, ask other traders for their advice.
The more you trade, the better you'll get at it! It takes practice and time to learn what trades are truly fair and which are unfair.
Once you've finished a trade and gotten your desired item(s) be sure to thank the player you traded with.