When I was in university, I used this method to improve my command of my body language and tone while partaking in competitive debating rounds.
Most people have various nervous behaviours and mannerisms that they're unaware of, and on top of that, most audiences are filled with people who are too nice to point out these mannerisms in a straightforward way. This makes it difficult to eliminate unwanted gestures that might signal lack of confidence, lack of focus, and other subconscious affects that detract from the effectiveness of your presentation.
Some common nervous mannerisms include:
- Fidgeting with an object like a pen, or with the hem of your shirt
- Wringing your hands
- Eyes looking off towards the side of the room
- Eyes looking down towards the floor
- Shifting weight between feet, creating a rocking back-and-forth motion
- Overly animated hand movements
- Arms swaying at sides
- Playing with hair or excessively touching your face
A really, really effective way to identify and eliminate these gestures gradually is to start recording yourself. Voicing over slides doesn't count; your body has to be in the frame, and ideally, you're standing at least five feet away from the camera so most of your body can be captured.
In university, I set up my webcam on a table, took four big steps back, and delivered my speech with the aid of a notepad. If you're preparing for a conference, you might want to use your computer to see your slides and speaker notes, so you can use your mobile phone instead as a recording device. You can buy a cheap cell phone "tripod", or a phone holder, to prop up your phone. If you have access to a projector or TV, I'd recommend hooking it up to your laptop and presenting with your back to it, so you get used to the motion of turning around to reference your slides (if that's a thing that you do).
I caught so many of my own awkward mannerisms this way. I also slowed myself down significantly this way, and learned to use more natural transitions. The first few times that you watch yourself on camera will probably be mortifying, but this is honestly one of the fastest ways to improve as a presenter.
You can make a list of habits that you catch yourself doing, and identify one or two to work on. Record yourself giving the same presentation again, and play it back again. I wouldn't recommend doing this more than once or twice a week; your brain needs time to digest how to process the things you're trying to change.
When you're starting out, it's hard to fully eliminate a habit. The key is to focus on reduction, and to try to understand if there are any external factors that prompt you to do those mannerisms. For example, do slides that are dense in written content tend to draw out nervous behaviour? Is it possible to redesign the slide with less text, so you can be more at ease while presenting it?
This message will be in a few difference places, but it's really important here: it's so, so easy to nitpick at yourself when you're watching your own recording. You will always be your own harshest critic, so please try to remember that this is about gradual improvement, not overnight perfection, and in order to make progress, you need to grant yourself forgiveness and kindness. You probably would never judge another speaker so harshly, so try to give yourself the space you need in order to get better at this discipline.