Never give out your password!
This applies to capitalism, communism, and indeed the Runescape Customer Support service.
They've asked me to point out that Jagex is still committed to the War against Scamming, but if you're ABSOLUTELY DETERMINED to give away your password and / or possessions, there's really not much we can do about it.
So please do not give out your password to anyone, and use the trade system to protect yourself from scams. If players ask you to "lend" them your items, or play games of "trust", our advice is to just say no.
It is up to you to accept or decline any deal that is offered to you- so you must decide if it is fair BEFORE you go ahead. Even with the best of intentions, sometimes money has a way of coming between friendships...