Every time I speak in public, I schedule two "speeches." First, there's my "left brain" speech, which is mainly factual. Secondly, there's my "right brain" speech, which is primarily inspirational. I thought about that when I was reading the book of Ecclesiastes in my morning Bible study. In Eccl. 12:10, we read: "For the Preacher was not only a wise man, but a good teacher; he not only taught what he knew but taught them in an interesting manner" (TLB).
There is no substitute for the meeting of the two brains, and the basics of public speaking are the same today as they were in Solomon's time. A great speech not only has great content. But the speaker also captures the audience's heart. Every eye is on him or her.
When I'm talking to a particular group of people, I change my approach to adapt to different personalities. If you don't make that adaptation, you're likely to fail. The distinction between a left brain talk and a right brain talk might be overly simplistic, but it proves to be very practical. People even write this way. Think of "N. T. Wright" (the name he uses in his academic works) and "Tom Wright" (the name he uses in his more devotional works). Or think of the difference between my purely informational beginning Greek grammar (Learn to Read New Testament Greek) and my more motivational intermediate grammar (It's Still Greek to Me). My favorite authors, while going into the ABCs, always insert just enough humor to make the facts palatable to right brainers.
Cicero (a great orator of long ago) once described the aims of public speaking as:
Ut doceat
Ut moveat
Ut delectet
In other words:
To teach
To motivate
To entertain
Telling stories helps. This is how Jesus often taught. Anecdotes and parables are windows into the speaker's soul. Speaking without notes is also a good idea. All too often a sermon is stale because the speaker is too busy scrolling on his iPad to connect with his audience. Interestingly, your audience will know whether you've put in the work or not. They hear the pain and sacrifice in your voice. That being the case, the more motivational the talk, the more likely the outcome will be memorable.
To summarize what Eccl. 12:9-10 is saying:
1. The Preacher was a wise man.
2. The Preacher taught the people all he knew.
3. The Preacher taught them in an interesting manner.
That's great advice for those of us who profess to be public speakers.