If presentations are not something you do regularly, then you need to rehearse what you're going to say and how you're going to say it. Work with someone in the office, a good friend or your spouse to smooth out the flow of information and make yourself as concise as possible.
Most of us have been in presentations when the presenter was out of touch with his or her audience, rambling on long after audience interest had left the room in despair. Think in bullet points and headlines. You want the attendees to come out of your presentation with just a handful of clear benefit statements about your product. Don't drown your competitive advantages in a lot of chatter about your company, your history or your golf game.