At one end of the public-speaking continuum, we have the tight speaker who reads from a script. At the other, we have the loose speaker who improvises delivery. In most situations, what we’re aiming at is to strike the happy medium between these two extremes, to know exactly what we’re going to say, yet to deliver it in a way that sounds natural.
If you begin by writing a script, even if you go on to speak from brief notes (or none at all), the risk is that you’ll still sound as if you’re reading, because you’re reciting something that was originally written, rather than spoken. On the other hand, speaking off the cuff is never going to be as focused, clear and effective as delivering something you’ve prepared and practised.
For inexperienced public speakers, a large part of the problem is the language that’s commonly used to describe the preparation phase: writing a speech is surely a contradiction in terms. Yes, there are those who excel at this task, particularly for formal, set-piece occasions (such as political speeches), but there are also people who can write novels or plays and most of us would not assume we could do that without training – or not for public consumption, anyway.
The happy medium between writing a script and improvising is developing your talk organically, by speaking out loud.
Think of a story from your life that you’ve recounted many times over the years. When you first narrated that incident, it probably wasn’t as well crafted as it is now. Over the course of repeated tellings, you’ve honed your wording, cut out any waffle and fine-tuned your punchline, so as to have maximum impact on your audience. This is exactly the process you need to apply to your speech or presentation.