I didn’t want to find her. Not now. Our bargain had been clear, and also inevitable; and there are advantages to sleeping alone. I’ll think of them i… - Larry Niven

3) Stories to end all stories on a given topic, don't.

Perhaps the lines of nationalism and factionalism and every other goddamn “ism” in the world had reduced the chances for this weary planet. Or not. Nuclear devices had existed for over a century, and only four of them had ever been used in anger. This could be interpreted as proof of divine intervention, good luck, a sign that the human race was growing up, or ominous portent, depending upon one’s standing in the “half-empty, half-full” school of cocktail-party philosophy.

4) It is a sin to waste the reader's time.