In the comments last week, there was discussion about how it's not always an "either or" situation. This is so important, and it shocks me that I never really talked about it before.
As with dramatic irony vs surprise, you don't have to pick one over the other. Mixing various techniques to achieve your writing goal often gives the best results. Layering plot leads to unpredictability, layering character development leads to deeper conflicts, layering dialog leads to character development. Just like you don't want setting details to just provide setting, everything you do with your writing can do double duty.
It's the braiding of words that create the richest stories. That can be the surface words on the page, the deeper meaning behind those words, or how we choose to put those words on paper in the first place.
- Look at your external goal and see what internal conflict you might be able to bring out to complicate that goal.
- Look at your setting and see what you can do to add to the mood or tone. Maybe even use that to illustrate another aspect of your character or foreshadow a critical moment.
- Look at your characters and see how their misconceptions can complicate things, or how a past trauma might affect a present problem.