Now I'm no Zen master or Buddhist monk when it comes to relaxing. But there are some things I do before giving a speech that help me to relax. 
It?s just like back at High school when you have to speak in front of the class, the teacher gives tips on how to relax, saying things like ?Just imagine everyone is sitting on a toilet.?
I?m not for a minute that you think like that, you?re mind should be on the task at hand, not worrying about what the audience says or thinks, it?s a matter of centering your attention and concentrating on your most desired outcome first, then the rest will follow. This technique is called ?Visualisation? and is the only way to prepare yourself mentally for the task you?re about to embark on.