[akkartik]

"Be prepared to back up your claims with documented, solid evidence of the behavior. Keep emotional, hyperbolic, prejudicial expressions or assertions to yourself - they will only work against you in such situations. Avoid ultimatums. Express faith in the system and the ability for the person to change. Express willingness to change yourself. In other words, come off as the bigger person right from the beginning and at all times."

Based on past bitter experience I've boiled this down to, "Don't be easy to dismiss."