Try weaning yourself from PowerPoint. Use less and less over time. When you do use slides, limit them to a word or two, maybe three. This way, the slide becomes a visual cue instead of a treatise to be read. You and your expertise become the conveyance, the show, the meaning, and the message.
You are the expert they selected. They want your perspective, your take on things. You can always send them the details later. Right now, your job is to deliver a message that engages them and then creates opportunities for them to engage as well, not only through Q&A but also in small groups.
Remember: they are experts too.
Avoid, at all costs, the familiar "turn to your neighbor and..." Instead, get people on their feet and have them form groups of three with anyone but their neighbor. In large groups, I often say, "And just for fun, let's do this in total silence."
You are not as important as your audience. Coaches often use the mantra WAIT: Why Am I Talking?
That's not a bad mantra for those of us on the platform, either. We learn very little by sitting, receiving, and, frankly, judging. In small groups, I'm not judging. I'm co-presenting. I'm engaged and aware. This can easily be coupled with time for the audience to process ideas together.
Recently, I listened to a well-known business author, one of my favorites. We even use his book in my university classes. He delivered a 90-minute lecture on his "new book." I don't remember a thing about the presentation except that I think he used the phrase "my new book" about 38 times, maybe 42. I lost count.
What was his takeaway message? As best I could tell, it was: "Buy my book." It could have been so much more. It could have been about us.