1. Focus your presentation. Having a long, rambling presentation that is hard to follow is not going to win you any audience interest. You need to make sure that your presentation is clear and focused and that any asides you throw into it are there to back up the main point.
• It's best to have 1 main thesis statement or overarching theme and 3 main points that back-up or flesh-out your main theme. Any more than that and your audience is going to start losing interest. This means that any facts and information that are apart of your presentation should back up these 3 main points and overarching theme.
• For example: If you're giving a presentation about 17th century alchemy, bringing up the history of alchemy is fine (and probably necessary), but you don't want to mire your audience in its history instead of focusing alchemy in the 17th century. Your 3 points could be something like "alchemy in public opinion," "famous 17th century alchemists," and "the legacy of 17th century alchemy."