Improvisation is one of the most important skills an actor can develop. Also known as ad-libbing, improvisation requires no script, simply the actor's imagination as he makes up the plot and dialogue of the scene on the spot. For a public speaker, improvisation can be useful on occasions when it's necessary to depart from the prepared speech and address specific facts about your audience, or reference something significant that happened between the time the script was written and when you deliver the presentation.
Actors will often take a script and try to personalize the emotions and events their character is experiencing by relating these to experiences they've had in their own lives. In this way, the characters' feelings become real to them; they're not simply pretending to be those characters but feeling real emotion, because they now have a connection to the characters' experience. Public speakers can tap into this same technique by personalizing stories by placing themselves within the anecdotes by using imagery and detail. Even if you're describing something that happened to someone else, try to connect this story to an event in your own life in some way.
It's something of a cliche in the theatrical world for an actor to ask a director, "What's my motivation?" Yet this is a crucial part of an actor's preparation; unless the actor has a solid grasp of why his character is behaving the way he does, he won't be able to accurately portray the character. Motivation is also important in public speaking. The difference, however, is that an actor is playing a character, and you, as a public speaker, are being yourself. The key is to have a strong understanding of the points and messages you're trying to get across. Keeping your core message at the heart of your presentation or speech will provide a sense of purpose and ensure that your points are made effectively.
An actor must be able to be relaxed onstage, which leads to improved concentration while performing. As a result, actors have developed various relaxation techniques designed to reduce anxiety and free the mind to focus on the performance. These include breathing techniques, visualization exercises and even self-hypnosis, which allows you to self-suggest positive affirmations to increase confidence. When giving a speech, it's important that you seem calm, relaxed and in control. If the audience senses your anxiety, it will make them feel anxious for you, shifting the focus away from your message.