What are the essential qualities of great public speakers? What makes them more persuasive? How do they influence people to take action?

I've seen lots of presenters and lots of presentations-but some stick in my mind more than others. Why?

This is my attempt at delineating the traits and habits that make people memorable and effective as speakers and presenters. I list them here in no particular order.

1. Great Speakers Know the Basics

Great speakers need to know what ancient wisdom and modern science have to say about the best practices in constructing and delivering talks that work. If they don't know this-the principles of rhetoric and oratory-they wander around in the dark trying to reinvent what was long ago invented.

2. Great Speakers Demonstrate Purpose

A great speaker knows his stuff and cares about a particular topic. His passion will convince others, not just because of his force of reasoning, but also because he is visibly enjoying the beliefs he wants his audience to accept.

3. Great Speakers Show Personality

A personality is what makes a person distinct. We all get one at birth, and many of us lose ours when we set foot on a stage. It needn't be a warm personality, although warmth is an attractive quality. It just needs to be real, determined, and accessible. Listeners crave intimacy with speakers.

4. Great Speakers are Inventive

A great speaker needs to create presentations and speeches. She needs to say plain things in interesting ways, and interesting things in plain ways. One can be a good speaker without creativity, but greatness comes from inventiveness, from cracking open a coconut with a feather and finding inside a little old man in a plastic chair sipping a pia colada.

5. Great Speakers Make Connections

Listeners live on an island of their own interests. Great speakers build a bridge to that island: They can make a conflict in Ukraine rattle the dishes in your cupboard in Kansas.

6. Great Speakers aren't Fancy

Great speakers keep it simple. They use short sentences. They use everyday language to make complicated topics clear and understandable. They don't show off their knowledge by using a specialized vocabulary. They use metaphors that appeal to all of us, such as, "On healthcare.gov, you can buy a Rolls Royce, a Chevrolet, or a junker policy, and they all cost more than they used to."

7. Great Speakers can Fail

Like every other human being, great speakers walk forward on two legs: trial and error. There is no such thing as a perfect presentation. Every effort is a new experiment. Great speakers fail their way to success. A speaker who is not willing to fail will not be great.

8. Great Speakers Work at it

A great speaker needs the constitution of a horse. Laurence Olivier said this about actors. Life on the stage takes a lot out of you. You need high energy, low tension. Your adrenal glands will work overtime. You'll have to get up early, stay up late, and wake up in the middle of the night-to write, to get it right, to make it work for a different audience.

9. Great Speakers Keep Things in Perspective

A great speakers needs rhino hide. He or she must believe in self and message, or else be a skilled actor. And even though success may depend on the opinions of others, one can't care too much about what people think. And by the way, the more popular you get, the more people dislike you. Look at the president. If 51 percent of the people like him, 49 percent don't.

10. Great Speakers are Vulnerable

There's nothing worse than an old workhorse of a speaker with rhino hide who loves to hear himself talk. It was Warren Harding's speechwriters who invented the word bloviate to describe the president's ability to talk much and say little. Vulnerability can help a speaker say a lot without talking much. It can make him more sensitive, real, and accessible. Humility is attractive too, as long as it's not false. Ted Turner once said, with his tongue in his cheek, "If only I had a little humility, then I would be perfect..." thus revealing he had perspective on his egotism.

11. Great Speakers Have an Expressive Voice

The voice of a great speaker sparkles with change: changes of pitch, volume, and speed. A great speaker's voice is animatedly alpine: It goes up and down, it purrs and it roars. Since it's the only instrument in the orchestra, the voice of a great speaker is never monotonous. Its pitch, volume, and rhythm are always changing.

12. Great Speakers Display a Sense of Humor

You don't have to tell jokes, but it's nice if you can come across as having a sense of warmth and ease. When asked what are the most important elements of any speech, Kennedy's speechwriter, Ted Sorenson, said, "Brevity, levity, and charity." I don't think he put them in rank order, but if you can make people laugh, you have an unfair advantage over speakers who can't.

13. Great Speakers Dress the Part

Men first.

I am not a big fan of men wearing wrinkled pants. And men, unless you're built like a whippet, you look better in a jacket tailored to improve your profile. You don't need a tie all the time, but a couple of really nice-fitting standard-issue suits in gray and blue will do the trick. You should be able to button your jacket and wave your arms around without busting your buttons.

Leaders of large companies and large Western nations tend to wear black shoes with their conservative suits and ties. In certain regions, brown shoes are permissible.

As for women, formal business attire is a business suit or pants suit, or dress and jacket. Business casual is a shirt with a collar and/or a sweater, khakis or dress pants, and nice shoes. Watch the height of the heel.

14. Great Speakers have Stories to Tell-and Work to Get Them Right

And yes, you should tell stories-to demonstrate who you are, and to illustrate your points. They should be your own stories, not borrowed from another source. Your own stories have a sterling ring of truth.