Pretty much every budding writer has that moment of sick uncertainty that's triggered when someone tells them that they're breaking one of the cardinal rules of writing. The internet makes this an almost everyday occurrence for those of us who frequent writer's forums. Never before has so much free advice been at humanity's fingertips.
But there's a downside. Everyone and their dog has a blog (including yours truly), but not everyone's opinions are well informed. Some of the so-called rules are good general advice or guidelines, but even so, they have exceptions. Others simply leave me scratching my head. Guidelines are good. It's important to know where they came from and why they exist. If you choose to break them, it should be done with a clear purpose in mind, and you should solicit feedback from people you trust to tell you whether you've done so effectively. But you don't want them to become a narrative albatross around your neck.
Here's a rundown of some of them.
1. Never start a story with someone waking up. I think the truth behind this one is that novice writers will sometimes start a story with their protagonist getting out of bed and going through the boring routine of getting ready for work, all leading up to that moment when the boss says "You're fired!" or they have an accident that throws them into another dimension or find a magic frog or whatever. But unfortunately, many writers take this advice to meant that you can't ever have a story start with someone waking up, even if they're waking up to something very interesting.
2. Never show dreams in stories. Like the waking up thing, dreams can be used in a clichéd or boring manner. One of the worst is the scene that the reader thinks is an exciting (and real) event that turns out to be a dream. Dreams are rarely mistaken for real life when they're described to someone who isn't asleep (if I'm telling you how my cat turned into a racehorse last night, then perched upside down from my ceiling, it might clue you in that I'm telling you about a dream). But if a trip into the dreamscape advances the plot or reveals something important about a character, then it may work well. And of course in fantasy or magical realism novels, dreams can be real, or at least have real consequences for a character. There are plenty of stories where dreams figure prominently. Lathe of Heaven, for instance.
3. Never use flashbacks. Like dreams, flashbacks can be overused or clichéd. Writers fall in love with their back story and sometimes make the error of thinking that their readers need a detailed picture of every traumatic event that ever happened to their protagonist. But when used properly, flashbacks are a legitimate literary device, and one that appears in many classic and contemporary novels.
4. No contractions in the narrative. I seriously don't know where this one comes from. It's probably something people remember from their college composition classes (though I don't remember my teachers ever forbidding them in all circumstances). This used to be the rule for formal, non-fiction and technical writing, though it's one that's been relaxed, even in those contexts. It hasn't been a norm to leave contractions out of fictional narrative since at least the middle part of the 20th century. Don't believe me? Pull a stack of contemporary novels down from your shelves. Unless your taste runs to omniscient pov novels written in a very formal and old-fashioned voice, you'll find plenty of contractions.
5. Write what you know. This quote has been variously attributed to Mark Twain, Hemingway and other prominent writers of yore. It's meant to be applied to emotional experience, and as such it is good advice. If you've never been terrified of anything, it's probably going to be pretty hard to describe what fear feels like. But it's all too often taken by budding writers to mean you shouldn't write about any activity or event you haven't experienced directly. I've even seen people say they're afraid to write opposite-sex characters because they're only supposed to "write what you know." Think of all the great works of fiction that never would have come into being if writers took this literally.
6. Always show, never tell. A good writer knows when to provide those little details. It's particularly easy to filter over emotions, to say, "she felt angry," rather than describing what her anger feels like and what she does and thinks as a consequence of her anger. But there's a place for summarizing and taking shortcuts in writing too. Sometimes it's all right for a character's eyes to scan a crowded tavern without describing every battered oak table and smoky beam. You want your reader to see and notice the details your pov character would see and notice and to skim over the things the pov character would skim over.
7. Never use adverbs and adjectives; never use passive voice; never use to-be verbs or participle phrases and all those other rules about specific sentence constructs. Lazy or careless overuse of any of these weakens your writing. Each of these has traps that a writer can fall into. But each of these forms is a part of the English language for a reason. A quick perusal of pretty much any published novel will find all of these sentence structures. Some use them quite a lot. We can quibble about whether or not the author in question had to do it that way, or whether changing their style would make their work more enjoyable. But it's clearly not stopping them from selling novels.
8. Don't ever use clichés. Obviously, you don't want to lace your novel with trite and thoughtless turns of phrase. But some clichés are widely used for a good reason--they evoke a clear image and can establish a frame of reference, and possibly voice. And of course, anything that's written "in character" may contain clichés if they're true to that character's voice and experience. If your pov character is the kind of person who would say that someone is slippery as an eel, then including it will reveal something about that character. And there's nothing more painful than a simile or metaphor that feels forced because the writer is struggling not to use a cliché.
9. Never use any verb but said to tag dialog. Said should be the default dialog tag. It's also all right to occasionally have characters ask or answer. These words tend to be invisible to the reader. But more descriptive tags do have a place. If you need to call attention to the fact that your character is shouting above the clamor of a battle, or that she's leaning in and murmuring something to the person sitting next to her, then it's perfectly all right to do so. What you don't want to do is to use "colorful" tags frequently (as some newer writers do in the mistaken assumption that said becomes repetitive). Another mistake is when writers use actions that occur right before or after something is said as tags. People rarely cough, laugh or snort words.
10. Never use exclamation marks. We're often told that the words or associated descriptions should let the reader know if something is being said emphatically. But they're a valid form of punctuation, and it's perfectly all right to use them in dialog, and even in deeper pov narrative. The problem is when they're used so frequently that they lose their punch or start to look like a pair of teenaged girls are texting one another (of course, if your story is trying to depict two teenaged girls texting one another, this may be just fine).