Since I joined a couple of writer critique groups back in the early 1990s, I learned a lot of basic guidelines for good writing. The majority of them made a lot of sense to me. And as a reader as well as a writer, I now notice some awkward, clunky writing that miss the following points.

• Stay in point of view—no head-hopping inside a scene.
• Write as much as you can in active voice; don’t be passive.
• Leave out the boring stuff.
• Use modifiers sparingly (some say not at all, but I don’t agree with that—see below).
• Never use a semi-colon in fiction. (I break this one every so often, just because I’m a rebel.)
• Learn and use all the rules of grammar.
• Spell check over and over again.
• Get critiques and edits.

Then there were other rules I had trouble with:

• Show, don’t tell. In my opinion, this can lead to choppy writing and lack of interesting details. Yes, show action, but tell descriptions.
• No prologues. Come on. Sometimes they’re exactly what’s needed. They can pull the reader in and explain some backstory so there’s no “info dump” later on. I agree, though, that they need to be done very well. Many best-selling authors use them. Why shouldn’t the rest of us?
• No epilogs. I have two reasons for using them in my Paula PI books—one is that as a reader myself, I like to know what happens with some of the characters later on. In a mystery in particular, it’s hard to wrap up all the loose character threads during the hopefully action-packed ending. The second reason was simply because it was a senseless rule. (There’s that rebel again).
• Don’t use he said/she said. Have the character do something instead (cough, sigh, drink coffee, drink beer, whatever). Sorry, after a while of reading all these small actions (especially the coffee drinking) it gets old AND intrusive AND boring. He said/she said is invisible to most readers. It doesn’t stop them. So, why not use it? I do both the saids and the small actions, mixing it up.
• Split infinitives are evil. Only if you’re an English teacher who hasn’t kept up with the times. When Latin was in use, this was a necessary rule. It’s not one for those of us who speak English. And sometimes splitting the infinitive makes the sentence much stronger: “to boldly go where no man has gone before’ has a much better cadence than “To go boldly where no man has gone before.” Right? Right. When we were motorhoming I found a great bumper sticker that we promptly put on the couch: “Boldly going nowhere.”

But I digress.

One warning about head hopping:

If you do head hop between scenes, be sure the reader knows right away whose head you’ve hopped into if you’ve changed it since the last scene. The book I’m reading currently has made this mistake several times, and it always make me stop in order to figure out I’m in a different head.

So, the biggest rule is to do what works. What works is smooth writing that doesn’t in any way make your reader stop reading to figure something out. This is okay for non-fiction. Not so much for fiction. Thus the rules about using good grammar and spelling in particular.