Whenever you put together a presentation, you want to picture yourself as a storyteller. Unlike a paper, you don’t need to go into fine detail unless it helps deliver you to your final punchline. There should be only one main punchline that you want everyone to walk away from the talk understanding, and at most two or three minor points that it’s okay if not everyone takes away. Your main punchline, though, is something that you need to keep hammering them with throughout the talk.
When you’re building your talk, you need to know your own comfort levels and speaking style. Often students will start off with a lot of slides in their talk, and each slide will be covered in words. This structure is helpful for early talks, especially if you’re concerned about being nervous and forgetting what you wanted to say. As you get more comfortable speaking, I highly recommend you reduce your number of slides and the number of words on them, instead focusing on pretty pictures and videos that you talk about. A good speaker will often have only one slide for each three to four minutes of speaking.
Every time you change slides in your presentation, you lose your audience for a moment as they take in the new slide. The more material on that slide, the longer you lose them for. If there are a lot of words on the slide, some members of your audience will be reading those words rather than listening to what you have to say. Remember this, and do what you can to keep control over their attention. If you put up a quote, start reading the quote to them almost as soon as it appears (if they get slightly into it before you start reading, they’ll instinctively wait for you to catch up). If you are going to put up a complex graph or diagram, reveal a piece of it at a time, and explain it as you do. For example, if you are going to put up a graph with many different lines on it, put one line up first, and make sure the audience fully understands that line before you add on any more.