Keeping that fourth wall down.
When a character in a play steps out of a scene and reveals his or her awareness of the audience, it’s called, “breaking the fourth wall”. The fourth wall is the imaginary wall that normally separates the characters on stage from the audience in the theater.
In a presentation, you should be breaking the fourth wall the entire time. After all, you’re directly addressing an audience.
In fact, you never want to build a fourth wall during a presentation. That is, you never want to ignore your audience and start talking to yourself.
It sounds funny, but people talk to themselves during presentations all the time. We've all seen it, and most of us are guilty of having done it. It happens most often when something goes wrong.
Stop yourself from muttering little comments under your breath (e.g. “Oops. Hold on. What just happened?”). As awkward as it can feel on stage, it looks much more professional to pause silently for a few seconds when you need to regain your bearings.
Avoid talking about your presentation tools (e.g. “How do you use this remote?” “Is this video working?”). And, most importantly, don't face your slides as you talk. Your slides didn't come to see you speak, your audience did.
Learn to always keep your audience in mind, keep that fourth wall down, and you'll immediately see a major improvement in your presentation delivery.