From Nathan Bransford:
If you hand off your novel to a loved one and you can’t help but notice their attention wandering, it might be more than their unfinished game of Wordle that’s getting in the way. You might have written a novel that’s more confusing than you think.
I’m going to round up a list of reasons you might be confusing your reader.
You might have thought of before some of the first ones on the list, but they’re still worth a gut check, sort of a “did you try turning it off and turning it back on” level of writing advice.
But stick with me here, because I’m going to get to some you might not have thought of before.
You’ve lost sight of what’s actually on the page This one is basic and fundamental. As writers, it’s nearly impossible to avoid projecting things onto the page that just aren’t there. Really ask yourself: Can I see what is and isn’t on the page?
You know what settings look like, why characters are doing what they’re doing, and why there’s a gargoyle playing pickleball atop every gate in your novel. Unless those details are actually on the page, the reader is going to be confused.
Every single writer struggles with this to some degree, which is why editing is so important, but some writers struggle more than others to put themselves in the shoes of someone who’s coming to their work fresh. Unless you can build that empathy muscle for your future readers, chances are you’re going to end up with a book that readers find a bit mystifying.
The perspective is broken A novel’s perspective is absolutely fundamental to the reading experience. It helps determine where the reader situates their consciousness within the scene they’re constructing in their head.
If the perspective is omniscient, we’re anchored to an all-seeing “guide” who steers us around a scene. If it’s limited or first person, we’re tied very closely to a particular character.
We contextualize what happens in the scene with that vantage point in mind. For instance, if a first person narrative voice refers to a “he” within a scene, we know the narrator is referring to the man he’s talking to. If the perspective is unclear, we may be confused which character the “he” pronoun refers to.
When the perspective is a mishmash, we will quickly struggle to make sense of things and will feel extremely disoriented. Make sure you know your perspective, and keep it utterly consistent.
Your writing is imprecise or needlessly convoluted The more energy the reader has to spend parsing sentences, the less they’re able to simply focus on the story.
Now, let me be clear that I’m not saying every single sentence needs to be as taut and spare as Hemingway. It’s okay to be flowery and interesting if you want to. But unless you’re explicitly aiming to create something challenging or experimental, err on the side of precise, elegant, and digestible.
Sharpen your physical description and make sure readers can visualize their surroundings, don’t bog things down with needless details about everyday objects, clear out the clutter around your verbs, and read your prose out loud to catch convoluted phrasing.
Precision is everything.
You’re trying too hard to be mysterious Sure. We all love a good mystery. And sometimes authors are so worried they’re being boring they try to make every single micro-moment in their novel mysterious.
When they do this, they can easily cross a line where it stops being mysterious, and instead it’s just annoyingly vague. It’s exhausting to try to follow a story where a character is running around doing confusing things for confusing reasons. You’ll wear the reader out if they’re left to only grasp at what is happening entirely from scant clues.
Make sure the reader is well-situated in the story, choose your mysteries very judiciously, and try to build mysteries around whether characters will succeed or fail. It’s hard to feel anticipation for an impending encounter if we have no idea why the dragon they want to slay is important in the first place.
Link to the rest at Nathan Bransford
PG notes there are lots of links at the OP to additional information on the items Mr. Bransford discusses.

