One other tip: rehearse into an electronic recording device where you can: 1) time it and 2) hear what you sound like. You’ll hear where you stumble, where words or ideas are not clear. And timing it is important. You don’t want to end up being either rushed because you have more material than the time available (and be tempted to talk too fast) or run out of material (although you can always have a Q&A session planned, or have extra material available).
Remember, you’re giving the talk because somebody thought you had something important to contribute. The audience will respect that and will go in expecting to hear something good. You’re up there because you’re the expert. Be confident.
Above all, relax. Your audience will have a certain amount of empathy for you; they will feel what you are feeling. If you’re relaxed, they’ll be relaxed. And if they’re relaxed, they’ll be more open and receptive to what you have to say.
Bill Murray: “The more relaxed you are, the better you are at everything: the better you are with your loved ones, the better you are with your enemies, the better you are at your job, the better you are with yourself.”