The easiest way to improve your presentations is to record them and watch yourself on video. At least that’s the theory. In reality, most people get more confused watching themselves than they did giving the presentation in the first place. They either get too hung up on things they don’t like about themselves—voice, hair, posture, etc.—or they see what they want to see and not what’s really there.
I use a 1-2-3 approach to watching video of a presentation. This balances positive self feed back with valid criticism with a vision for future performances.
You still may not love the way you look or sound on video but your skills as a presenter will definitely improve faster and more significantly.