asks: "How about plot twists? A good story always has a few plot twists to keep readers interested."

Plot twists are excellent for elevating a story from "interesting" to "Wow, I did not see that coming. Cool!" It makes the story memorable. Sometimes even mind-bending. In the movie, The Matrix, it took me several long moments to wrap my head around the fact that he wasn't actually a normal guy living his life in a normal world.

Maybe the reader suspects a twist is coming up, but when it surprises them anyway, the implementation was successful.

When Neo in The Matrix discovers what his reality really is, it launches the story in a whole different direction!

Readers become emotionally invested in the characters they read about. They care what happens to them. When you lead a character through so much turmoil and sorrow and triumph, and then they suddenly wake up and the entire story turned out to be a dream, the reader feels cheated. It's a plot twist, yes, but not one a reader will particularly like. Because none of it actually happened in the story. I've seen movies like this, and I usually come away thinking, "Well that was stupid." I felt cheated for being led through an entire plot that didn't actually happen. (As always, there are exceptions. Because exceptional authors know how to do it right.)

Start with something "normal". Maybe even predictable. For example, a new student at a school for vampires. People have seen this kind of story before, and think they know what's going to happen next.

Don't make hints about the plot twist too obvious. Maybe the clues can be subtle. For example, the new student puts up a poster of idyllic woods and bright sunshine. Or maybe the clues can be buried amid other details. For example, she unpacks her clothes, her toiletries, and a box of granola bars.

The fun of a plot twist is when tensions are high, BAM! Things weren't what you thought they were! On the other hand, if it gets revealed in a flippant oh-by-the-way manner, it falls flat. In our example, an exciting way to reveal it could be her best vampire friend is somehow stuck outside at dawn, with the sun threatening to turn him into ash. The main character must do something in the sunlight to save her friend. So after much angst and worry, she just does it. Runs into the sunlight, toward the shade where her friend is cowering. And nothing happens to her. The sun doesn't hurt her at all. Could she not be a vampire after all??

You can have more than one twist. Now that we're on this path, think about what the reader might expect now. Maybe now we think the main character is human, or a vampire who is immune to the sun, or maybe she just found some really good sunblock. Think of what kinds of cliches you could still fall into and avoid them. For example, a cliche might be to make her fall in love with the guy, and she decides she wants to be a vampire now, and oh no it's Twilight all over again. Try to come up with something unexpected. Like, maybe she does fall in love with the guy, and they're making out one night, and the moon is all romantic and full... and she turns into a werewolf! Whaaaat? Plot twist!

See how that works? It takes a certain awareness of reader expectations, and what has been done already. This is yet another reason to read a lot. Watching a lot of movies helps too.