It is an ancient truism that we learn to do by doing. The first thing for the beginner in public speaking is to speak—not to study voice and gesture and the rest. Once he has spoken he can improve himself by self-observation or according to the criticisms of those who hear.
Experience, then, is not only the best teacher, but the first and the last. But experience must be a dual thing—the experience of others must be used to supplement, correct and justify our own experience; in this way we shall become our own best critics only after we have trained ourselves in self-knowledge, the knowledge of what other minds think, and in the ability to judge ourselves by the standards we have come to believe are right.