This has made its rounds on the internet for quite a few years. I'm sorry to say that I don't know who the original author is. I may have added one or two items myself. I can't remember now. :-)
1. Avoid alliteration always.
2. Prepositions are no words to end sentences with.
3. Avoid clichés like the plague.
4. Employ the vernacular ad nauseam.
5. Eschew ampersands & abbrev., etc.
6. Parenthetical remarks (however relevant) are unnecessary.