Some people might find starting a posting id a really good idea.
For starters it means you can say anything you like.
Secondly it means you can say anything you like.
Within board policy of course
And if people don't like what you say they can't like, buy something off you and like, get your address details. And like, go and stand outside your house wagging their finger at you crossly - or something even more sinister. They can't auction bomb you either (but if you're really smart you can prevent auction bombing by editing your selling preferences)
Here is a link that explains the whole posting id thingy a lot better than I can.