Every writer has things they won't do when they write. Some of this is taught by that rule-wielding monster commonly known as the high school English teacher.
I've struggled for years with using the word said as a dialogue tag. One of my English teachers insisted that it was a flat word, and demanded we use more exciting "audible" words (like retorted, snapped, shouted, whispered, etc.) I was 13, she was 45; I figured she was right. When I turned pro, I found out very quickly that nearly everyone uses "said" and nothing else (evidently because Stephen King convinced them only said is an acceptable dialogue tag.)
Who's right, my English teacher or Stephen King? Let's put it this way: who's made a gazillion dollars writing books?
One article that I think positively influenced me on what not to write was written by an astronomer named Paul W. Merrill, and originally published in the January 1947 issue of The Scientific Monthly. Merrill was actually spoofing how-to articles by presenting one on the principals of poor writing (as in, how-not-to.) He was pretty funny, too, although he drifted off on a Shakespearean tantrum in the middle of it.
There were three points Merrill made on how not to write that just sounded right to me, as follows:
1. Ignore the reader. "The world is divided into two great camps: yourself and others. A little obscurity or indirection in writing will keep the others at a safe distance; if they get close, they may see too much."
2. Be verbose, vague, and pompous. "Avoid being specific; it ties you down. Use plenty of deadwood: include many superfluous words and phrases."
3. Do not revise. "Have no plan; write down items as they occur to you. Hand in your manuscript as soon as it is finished. Later resist firmly any editorial suggestions. Be strong and infallible; don't let anyone break down your personality."
Holly Lisle tickled me when she wrote a slamming article here that expands on the same theme.
I'm still wrestling with said, but here are a couple of things I've added to my personal how-not-to list:
4. Use a proper opener. Never begin your book with an interesting hook; it's vulgar. Always start with the weather, preferably a variation of It was a dark and stormy night.
5. Be decent. Never stray beyond the boundaries of what is politically correct. Keep things bland, safe, and innocuous so as not to possibly offend anyone.
6. Stay in the herd. Be sure to imitate bestsellers rather than discover your own voice. Clone everything they do so that you sound exactly like them.
What's on your list?