Lifehacker has a nice article on improving your public speaking.
Years ago I took a week long class in public speaking at the company where I worked.
It started out with video taping a short impromptu speech. We didn’t get to see the results of the tape at that time. Later, we talked about many of the basic of better public speaking: eye contact, cadence, pacing, etc.
Two of the areas that I had struggled with and, to some extent still do struggle with, are pacing and non-words.
I speak fast, especially when nervous. I can also be a quiet talker.
In the course of the class I became much more aware of controlling the non-words (Um, ah, uh, etc), more aware of pacing and the value of a pause, a moment of quiet to gather your thoughts.
At the end of the class we were video taped again and when we graduated, with certificate and all!), we received the tapes of our opening speech, several that we’d done in the middle and our final speech. The difference in that time was pretty striking.
I’m not nearly as concerned at the notion of talking with a group or even one on one with a stranger as I used to be and I credit that class, along with time and practice, with helping me to be a better speaker.
And, the far and away best recommendation from the above article is to record yourself and review it while practicing your speech. Pay attention to non-words and pacing. Look at body language and work on eye contact. The latter two won’t be natural when practicing alone, but it’s still useful. And, best of all, if it is possible, record the presentation itself. You may find it a bit cringe-worthy, but the feedback you’ll get from that will be invaluable.