One of those constantly talked about pieces of writing advice is tension. Make sure your story has tension. Let the tension ebb and flow. Raise the tension. The big question a lot of advice skirts around is where tension comes from, and how you manage it.
In the short term: tension comes from conflict. By definition it’s the stretched force between two opposing forces. It’s not unlike the rope in a tug-of-war game. Two opposing goals are straining to pull each other over.
Speaking long term, tension is the long-term driving force behind conflict. If there’s no obstacle to your character getting their goal, there’s no tension. However, if you add in obstacles, then there’s more conflict. That additional obstacle creates tension because it stretches out the space between your character deciding on a goal and achieving it.
When starting out on creating tension, take a look at what obstacles your characters have to go through to get to their goals. What could possibly get in their way? This might be another character’s goals, or a particular requirement such as a law or deadline, or even a physical complication such as a locked dor. Obstacles create tension because your character must solve them in order to get to their goal.
If you need to ramp up the tension, add stakes. This is where your conflicts can go from simple to tense. A character who needs to find a piece of paper has a conflict: they’re missing a piece of paper. It’s a conflict, but what happens when you make that paper the last letter they had from their late sister? That’s personal stakes, ones which create more conflict because it’s a moment of their late sister. Need that tension to be even greater? make it the last letter from their late sister which they need to prove her innocent, posthumously.
Tension and conflict often build of each other, so if you’re feeling a section of your story needs more of a driving force behind it, take a look at the tension. Consider if you have enough obstacles to keep your characters busy, and if their stakes are high enough to keep them invested in solving their conflict.