Effective communication is achieved with a good presentation, good moderation or good exposure depending on the type of event in question, and -I always emphasize this especially- regardless of audience and size.
There are five essential points that I recommend taking into account before any public performance.
The first is the importance of staging versus the content. I regularly observe a tendency, especially in more technical subjects, to focus on the content, when this only represents one fifth of the exercise. Mastering the staging is key, and fundamental to achieving a successful presentation. The second point is something I consider extremely important: body language. We are so transparent that our way of acting says everything about us. The third point is equally vital: tone of voice and pauses between speech. Our intonation and way of speaking is essential, particularly the pauses we take as we speak, which are precisely where the strength of a talk lies. A presentation of interesting content loses all its value if it is executed at full speed and without pauses. The fourth issue to be taken into account is the preparation. It is always very obvious when a presentation has been well or poorly prepared, and a good and thorough preparation connects us with the audience and also helps the speaker feel considerably more secure. My fifth point relates to those precious first thirty seconds considered as one of the most important aspects of any performance, and therefore requires careful preparation. I call this a Megaclassic. You have thirty seconds to connect with the audience and catch their attention. If this is not achieved in the first few seconds, it becomes a little more difficult to do so during the presentation.
You can see everything in a little more detail here: