This rule is for professional articles, presentations and other strictly informational content. Tell ’em what you’re going to tell ’em; tell ’em what you’ve got to tell ’em; tell ’em what you’ve just told ’em. This way they can read your piece once, or listen without taking notes, and come away with the main idea.
When you give examples, use three: “This is good because it emphasizes your idea, gives people time to think about it, and adds substance to your argument.” People like to read things in threes for some reason.
Whenever you move between ideas—usually in a new paragraph—you need a transition. It can be as simple as “However…” “But…” or “Next…” It can be as fancy as “Since memory is notoriously malleable, these reports can be unreliable. Let’s break down each report and look for inconsistencies.” Transitions signal the reader that something different is coming, and hint at, or state, what it is.
This isn’t about the three tells. It’s about getting tangled up with supporting details as your write your story. Very often, beginning writers put the same idea in different places in the essay. Mention the idea once, then expand on it with a few examples in the same paragraph or section. You can restate the idea in the ending, but don’t scatter it throughout your piece.
The end of your story should hark back to the beginning. Novelist John Irving actually starts his books by writing the last sentence, paragraph, or chapter. In many of his interviews he says something like “if I don’t know how my characters end up, how can I know how they got there?” Many of his books end with their titles or first sentences. That’s a trick, but tricks can be fun.