One thing I have learned in being in tech support is to sympathize with the customer.  Our service model is, "We are there for them and not the other way around." ...despite how idiotic they may seem.  Another important thing is to know your limits.  If you can't give them a viable solution or reliable information, be honest with the customer and tell them you will refer to someone that CAN give the correct answer.  Don't feed them B.S..