The best keynote speakers sound as if they are thinking out loud, as though the ideas have only just occurred to them. In reality, the talk has been prepared so thoroughly that it comes across that way.

Plenty of people refuse to write a script because they don’t want to look as if they are reading. They are right that reading a script on stage looks ridiculous. But skipping the script means doing only half the job.

Write the script, then absorb it until you no longer need it. Then cut it down to notes: three bullets per slide, no more than ten words each. That is enough to glance at and never enough to read. You will say it a little differently every time, but the flow will be in you.

Keep two other things in your notes: cues that make sure you hit a point, and any numbers you must get exactly right. In a keynote, a wrong figure can move a share price.

A script also tells you how long you will take. Count the words and divide by your speaking pace. And if you can’t script the whole thing, script the beginning and the end.