Your audience does not want to hear a mousy or timid speaker. Whatever you do, don’t let them see you sweat. You may be the world’s expert on the topic at hand, if your audience sees you sweat, some of them will think that’s because you are not sure of your subject.
This judgment is probably unfair to you. But perception is reality.
Your audience will always expect you to have more knowledge than they do on your presentation topic. After all, that’s why they show up to hear youn give a talk on your ideas. When they sense that you are nervous and seemingly unsure of yourself, they will tune you out and reject your ideas altogether. Remember that people seldom buy an idea without first buying the originator of that idea. They will judge your ideas by the way you present them.
Another tip: It is not necessary for you to cover all possible combinations and permutations in your presentation. You employ a technique known as “cognizant omission” used by many professional speakers. For example: You start by telling your audience that you have looked at all possible scenarios and you have narrowed them down to three that are worthy of further discussions. In that way, no one in the audience is going to think that you have ignored or overlooked some salient points of your argument.