We had a great workshop yesterday on pitching ideas for movies, books, and TV shows, with 40 participants. It was enjoyable to see people who were petrified at the start of the day gain confidence and begin to let their personalities emerge as they presented their ideas.
One of the misconceptions that people often have about pitching is that you have to put on some kind of song-and-dance-man persona. The opposite is true--you just have to be yourself, and to overcome your shyness or nervousness in order to let your self shine through.
One of the best ways to be less nervous is simply to know that you have prepared adequately--you know your idea well and you have some notes (maybe in the form of a mind map, or on index cards) to fall back on in case you forget.
The other thing to remember is to maintain good eye contact with the person to whom you are pitching, and to gently match their body language.
Of course there are many more things that can help, and I'm going to put together an ebook on this at some stage, but even just these few points above can put you on the road to making your idea sound as good as I'm sure it is.