Preparation and knowledge are the pre-requisites for a successful presentation, but confidence and control are just as important.
Remember and apply Eleanor Roosevelt's maxim that "no-one can intimidate me without my permission".
Remember also that "Depth of conviction counts more than height of logic, and enthusiasm is worth more than knowledge", (which in my notes from a while back was attributed to David Peebles, and I'm sorry not to be able to provide any more details than that).
Good presenting is about entertaining as well as conveying information. As well, people retain more if they are enjoying themselves and feeling relaxed. So whatever your subject and audience, try to find ways to make the content and delivery enjoyable - even the most serious of occasions, and the driest of subjects, can be lifted to an enjoyable or even an amusing level one way or another with a little research, imagination, and humour.
Enjoyment and humour are mostly in the preparation. You don't need to be a natural stand-up comedian to inject enjoyment and humour into a presentation or talk. It's the content that enables it, which is very definitely within your control.
You have 4 - 7 seconds in which to make a positive impact and good opening impression, so make sure you have a good, strong, solid introduction, and rehearse it to death.
Try to build your own credibility in your introduction, and create a safe comfortable environment for your audience, which you will do quite naturally if you appear to be comfortable yourself.
Smiling helps.
So does taking a few deep breaths - low down from the pit of your stomach - before you take to the stage.
From: Businessballs.com