You'll need 2 accounts, or you can just get a friend to help you.
This is very simple and will not get you banned, but is effective. I'm sorry if it's been posted.
You need an item, preferably something more 'unique' that won't be on the Auction House often, you choose.
Put the item on the auction house for a decent buyout, lets say 350 gold in this case.
Now get your friend to start saying the trade channel "WTB Destiny (or whatever item) paying 500 Gold! PST
People will most likely check the auction house, see it's listed for 350 gold and buy it out thinking they're going to make a very nice profit. So they buy it, you log off the alt.
This won't always work, but people have fallen for much more obvious things and as they say there is a sucker born every day, not to mention it's very easy to pull off.