Charm is that extra quality that defies description.
My botany professor created my lifelong love of plants because he was so enthusiastic about his course from the very first day. On that first morning he literally jumped up and down and said, "Ladies and gentlemen, guess what I have here?" Shivering with excitement he handed us a leaf, saying, "It's a living thing." That kind of attitude is contagious; the best speakers are genuinely excited about their topics. They have passion and aren't afraid to let it show. They know they cannot be neutral or apathetic if their mission is to persuade.
Whether you're facing an audience, active questioners, your boss, or a potential customer, it is your lot that your words tell only part of the story; the rest lies in how it's told. No matter how powerful or persuasive your words, your delivery will make or break your speech. Body language makes an initial impression with your audience, but it's your own style of delivery that will continue to shape those impressions. I still remember that botany professor because the way he presented plants was passionate. Look around and listen, and I think you will find it's the passionate speakers who are the powerful ones.
Use enthusiasm throughout your speech. With your opening words, show enthusiasm for both your subject and audience. Let your audience know you are delighted to talk with them.
Real enthusiasm leads to vivid presentations and makes your speech sound fresh to each audience, no matter how many times you have given it before. And you should take advantage of every actor's secret—make each time you speak about something seem like the first time.