(The list below is just a summary. See the original New York Times article for Leonard's entertaining explanations and examples.)
1. Never open a book with weather.
2. Avoid prologues.
4. Never use an adverb to modify the verb ''said'' . . . he admonished gravely. I have a character in one of my books tell how she used to write historical romances ''full of rape and adverbs.''
5. Keep your exclamation points under control. You are allowed no more than two or three per 100,000 words of prose.
6. Never use the words ''suddenly'' or ''all hell broke loose.''
7. Use regional dialect, patois, sparingly.
8. Avoid detailed descriptions of characters.
9. Don't go into great detail describing places and things.
10. Try to leave out the part that readers tend to skip.
My most important rule is one that sums up the 10. If it sounds like writing, I rewrite it.
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Once you've digested that, take a look at the Leonard obituary posted on The Onion, which deliberately breaks every one of the rules. What a sly tribute! (That's my exclamation mark quota for the day.)