Before creating any story, identify your theme. Your theme defines what your story is about. Until you know what your story is about, you risk writing unrelated scenes that make no logical sense. When you know your theme, then you can write scenes that not only work together, but also threaten the hero every time.
A theme defines a good and bad side. For example, the theme in “Terminator 2” is that “life is precious because killing is wrong.” Now study every scene and notice that the hero (the good Terminator) constantly faces this dilemma between killing and not killing.
When the hero is trapped in the SkyNet building, he shoots out the police cars and is pleased to see that he drove the police back without killing anyone. Earlier when the hero learns about not killing, he’s about to kill a bunch of guys who come running over to help John Connor after John Connor yells for help.
Every scene in “Terminator 2” revolves around this issue of killing or not killing. When Sarah Connor tries to kill the inventor of SkyNet, she’s faced with a choice between killing him or not killing him in front of his wife and son.
Notice that the theme also defines the villain’s actions. In “Terminator 2,” the villain (the liquid metal Terminator) is the rampaging killing machine who kills people without question. On the other hand, the hero (the good Terminator) is constantly forced to choose between the easy temptation of killing people to get what he wants, or the much harder path of not killing people to get what he wants.
So every scene pulls the hero in one direction or the other based on the theme. In “The Boy in the Striped Pajamas,” the hero is a young boy whose father runs a German concentration camp during World War II. The theme is that killing others hurts you as well.
So when the hero watches his father get praised by the Nazis for running an efficient concentration camp, the mother is horrified but the father treats his new job as a promotion that he needs to do his best to serve his country.
The hero winds up making friends with a boy stuck in the concentration camp and they play checkers through the barbed wire fence. Only until the end when the hero joins his friend in the concentration camp and dies in the gas chamber does the father finally realize (too late) that killing others hurts you as well, but in every scene, there’s always that dilemma.
So identify your theme and then make each scene reflect that tug of war between your theme and its opposite. The story is all about forcing the hero to choose and the hero finally chooses in the end.