Vocal skills include the range of a person's voice. Visual skills accounted for 55 percent of believability, vocal skills 38 percent. We cannot be detached from this that we preach. Everything about us has to be consistent and convey that message. Don't ever think that they're close to being the same thing.
Oral communication is very different, because it can communicate passion.
You want to make sure you don't do that. York suggested watching videotape of oneself in order to improve eye communication. The main thing is that you do want your hands and arms free. You don't want to have to be holding something. You want them free to move and to be consistent with what you're saying.