Something a lot of people do that create trolls within their games.

The unneeded comments that poke the troll within players.

The worst one of them all is "Why?" after a player makes a mistake and is most likely aware he made a mistake. This simple comment and many others similar to this is what will give birth to a players desire to troll/flame/rage.

Want to have less trolls? Then stop poking them. I mean unless you really do enjoy getting trolled.