I've been writing since the second grade, and in that (unfortunately long) time, I've met amazing writers, taken some incredible courses and workshops, and garnered a huge amount of writerly advice -- some asked for, some not.
I've learned that adverbs are a mortal sin (forgive me, writing Lord, for I have sinned. Repeatedly.)
That one character must die within the first five pages of a mystery, and the hero and heroine must meet by the end of the first page in romance or your entire manuscript is sunk (cue the iceberg).
A creative writing teacher once screamed that there was never a use for any dialogue tag other than "said." (See what I did there?)
I've been told that one should "write what you know" which either makes me a fascinating individual or the soon-to-be inhabit-er of a padded room with my very own straight jacket.
I've gotten advice on every writing habit, word choice, or career move I've ever made, but the best advice -- the advice I use on a daily basis -- came from a seven-year old kid. He was asked what he would do if, after coming home from a day of play, he found his front door locked. The kid shrugged and said, "I'd knock."
"What if no one answers?" the questioner asked.
"I'd just keep knocking until someone opened the door."
I had that phrase: "keep knocking until someone opened the door" taped in my office when I was querying editors and agents. I moved it to my computer when my manuscript was making the publishing house rounds. I rewrote it when my first book came out and I wanted people to review it. So why, four books later, do I still have that kid's wise words taped to my screen?
Because if you want anything in life -- to sell your first book or to become a New York Times bestseller, you could avoid all adverbs, kill and/or mate all of your characters, or write about your last trip to the dentist. All of those might help -- if you're willing to brave the elements, stand out on the porch, and keep knocking until someone opens the door.