Nick Morgan has some excellent advice. He wrote a paperback book called Give Your Speech, Change the World: How to Move Your Audience to Action. (An earlier, hard cover version was titled Working the Room: How to Move People to Action through Audience-Centered Speaking).
Don’t try to do just one rehearsal. You never will catch everything you would like to change in one pass through your material. Instead focus on one aspect or facet at a time. He says that you should do at least three rehearsals, and, if possible, seven. Nick says you should follow this sequence:
1. Rehearse the Content. See how long it takes to just get all the words out, and if your transitions work.
2. Rehearse the Logical Structure. Go through an outline of the main points (the essence or “spine” of your speech) and see how they connect with each other.
3. Rehearse the Nonverbal Conversation. You can’t do this inside your head. Try out your body language, gestures, and facial expressions. You should plan on doing at least these three rehearsals, and do more if possible.
4. Rehearse the Emotions. Map out your emotional journey, going from sad to happy as appropriate.
5. Rehearse the Technical Aspects. Do a walk-through using the notes, visuals, mike, camera, lights, etc.
6. Rehearse the Opening. Figure out how you are going to get a running start, so when you begin to speak you already are in the mood to shine.
7. The full Dress Rehearsal. Put it all together and, if possible, rehearse at the venue a day or two before show time.
According to Col. Larry Tracy the U.S. Army slang for a dress rehearsal is The Murder Board. That’s pretty grim terminology for a videotaped rehearsal! The Murder Board audience also has the job of coming up with tough questions for the speaker to answer.
In the second edition of her book The Complete Idiot’s Guide to Public Speaking Laurie Rozakis suggests the following sequence for rehearsing:
1. Practice the speech in front of a mirror.
2. Tape-record the speech, and then listen to it.
3. Videotape the speech, and then watch it.
4. Deliver the speech to a single person.
5. Rehearse the speech for a small group.
6. Eliminate distracting mannerisms.
7. Practice at the site.
8. Practice the speech using all the visual aids.
9. Practice with background noise.
10. Practice dressed as you will be for your actual presentation.
Laurie’s advice explicitly involves both getting delayed feedback on your own (audio tape & then videotape) and from audiences (of one & then more).
What should you NOT do to rehearse? Nick Morgan says to skip trying to rehearse in front of a mirror. Looking at your reflection in a mirror just makes most people self-conscious and awkward, unless they have already done this type of practice a lot. He also suggests that you get a live audience such as a child, or failing that a dog or cat. My advice is not to use a cat. Both of ours quickly get insulted and leave the room whenever I try to lecture to them.