From the writer's perspective, all this stuff we do comes down to one thing: keep the reader reading. If the reader doesn't keep reading, we've just wasted a bunch of time. Now, sure, we can say the writer benefits too. Many writers say they would write even knowing nobody would ever read their work. I'm not disputing this, but writers do what they do hoping someone else will read their work.
Keeping that one thing in mind, I see two aspects: keeping the reader reading right now, and making the reader come back for more later (for longer fiction, anyway.)
Keeping the Reader Reading
I could go into all kinds of thing here, but the one thing I want to focus on is conflict. It isn't some kind of magic. In fact, it's quite basic: someone isn't happy and something is in the way.
Bringing the Reader Back
Not surprisingly, this is related to the first thing. If conflict can keep them reading, it can bring them back, too. But we can only write about one thing at a time, right? So the solution is simple: we promise further conflict. That promise is what I call tension.
Any new writer will hear the advice to always have conflict. Every scene, every paragraph, every sentence, every word should be rife with tension. The problem I ran into was that it didn't work. It led to forced, contrived, tiresome scenes, paragraphs, sentences and words.
Until someone added that one simple element: the promise of conflict. It's still not easy, but things worked out better for me at that point.
Taking that further, one could even find a certain rhythm in the ebb and flow of conflict and tension, if one were so inclined.
So what about scenes that promise conflict, but don't contain any immediate conflict right now? Can they work? Yes. I call them incidents (a term borrowed from a fellow writer, but not an uncommon term in writing.) Incident leads to impact, and that impact is what brings the reader back. A car accident might have conflict: the paramedics are trying to save dad's life. But suppose we took that out—just a car accident. Sure, I might weave some other things in or just have it in the background. There's no need to drag an incident out, but it leaves questions hanging: what will happen to the kids now? Who gets the inheritance money?
Because of the ancient and unquestionable advice to always have conflict at every moment, some writers balk at this idea. It's not hard to find examples in classic literature, though. Gandolf shows up on Bilbo's doorstep. They don't argue or draw swords, but Gandolf's appearance promises trouble ahead for our little hero. The same is true of the rich heiress walking into the detective's office, or Katniss volunteering as tribute. She doesn't argue with the guards or struggle against inner demons, she simply does what is right and, in so doing, promises us that conflict is ahead.
Writer of speculative fiction. Current work in progress is an untitled dark fantasy novella.