Here is an idea that you are going to hate! But trust me, give it a shot, you won’t be sorry.
The next time you have a presentation to rehearse, record your rehearsal on video. I know, we all hate the way we look and sound on video. But it’s okay, get over it. After all this recording is just for you, nobody else ever has to see it.
I promise you will get a lot by recording yourself. You need to rehearse anyway (you do rehearse your presentations don’t you?) And who knows your subject better than you? So doesn’t that make you the perfect test audience. By rehearsing on tape, you can judge if you are speaking at a good speed, if you are able to maintain eye contact with your audience (the camera) without stumbling. You will get a pretty good idea of the length of your presentation, and you can test out your equipment, software and visual aids to make sure everything is in working order.
So start up the video app on your smart phone, or use the web cam on your laptop. Production value is not important. Remember this is just for you. Read your script over several times, not to memorize it, but just to be sure you are really comfortable with the material, then reach over and hit the record button.
When you are done, get comfortable and watch the playback. Take note of any changes or corrections that you would like to make. Feel free to do a second recording once you have run though the first, and hey, when you are done, feel free to hit the delete button!