To write solid action scenes, start by understanding humans. Action is almost always the result of overwhelming emotion. If inertia is the strongest force in the universe, you need something that shatters it. That something becomes the scene’s (and your character’s) DRIVER. Example: Breaking Bad. The US healthcare system failed Walter. Rage and desperation drove him and the series. Maybe you can see how that emotion also drove the rising arc of increasingly brutal action as the series progressed.
Once you have a driver, you take human physiology into account. It should be familiar. Fight, flight, or freeze. You must know your character(s) well enough to know what prompts would make them fight, which would make them run, and which would make them freeze. Characters can progress from one stage to another. For example, you hear a noise in the house at 2AM. You freeze. It’s in your bedroom! You throw off the freeze and run for your life. It’s a bat fluttering around the room. Now you slip into fight mode – not that you’re going to start swinging at the bat (unless you are – in that case, get on with your bad self) – you’re going to shift into action. You close the bedroom door to keep the bat contained, and you open your window so the bat can escape. Maybe you switch on a light to encourage the bat to land so you can grab it in a towel and yeet it from the window. The process can go in reverse, too. Fight first, run when fighting isn’t working, then freezing and playing dead when even running fails.
Finally, it helps to consider which kind of action scene you need.
An active scene is self-initiated. Action results from internal stimuli (emotion, desire, longing, etc.) Key identifier: A decision or choice is made.
A reactive scene is externally initiated. Action results from external stimuli or events (being pursued, being caught, someone throws a punch.) Key identifier: Surprise.
Active scenes tend to follow a galvanizing moment. Think of Star Wars: A New Hope. The Millennium Falcon gets tractored into the Death Star. Luke finds out Leia is on the station. She’s the reason he’s in this mess in the first place. His family was killed because of her droids. He makes the decision to rescue her. (It’s common for Active scenes to follow Reactive scenes – someone comes for you – now you’re going to decide your next action.)
Reactive scenes follow a shock or a surprise. Someone jumps out of a dark alley with a gun. At its purest, most primitive, this is the leopard chasing you across the savannah because it wants to invite you to lunch the hard way.
Driver. Fight, flight, or freeze. Active or Reactive Scene.
Now you need to know the purpose of the scene. You need to know what the protagonist and the antagonist stand to win and lose in the scene. How does the action serve the character arc and the story arc?
Next, sketch out the skeleton of the action beats in the scene. (Example: Vlad jumps out of the dark into Jenny’s path. She runs. Struggle at the doorway knocks free splinter of wood. When he hits her and she falls, she grabs the wood. He picks her up by the throat. She stabs him through the heart.) Now sketch in the dialogue if it’s necessary for the scene. Go back and fill in the POV character’s sensory and emotional detail. Use a light touch in a reactive scene (in the event that Jenny wasn’t looking for Vlad and this is a huge shocker.) Layer in more sensory and emotional detail if it’s an active scene (Jenny decided to go hunting Vlad, cause this girl is done.) Finally, flesh out the action. Focus on crisp, clear stage directions. Pierce Jenny’s hand with the sharp wood and let the blood run so you can lead up to driving that stake into Vlad’s heart. You don’t need every single move. You do need to plug any ‘how did they get there’, ‘where did that wolf come from’ holes in the scene.
Your action scenes need to result in emotion and thought after the action dies down. They should change the character(s), drive the story arc, and the character arc. Also, once you've done this layer technique a time or two, you'll just write an action scene without having to block it out so technically. And wow, hasn’t this turned into a whole-ass treatise?
Which means it’s time for the standard disclaimer: This is only ONE way to write action. It’s a tool I find useful. Pick it up. See if it fits your hand. If it doesn’t, toss it like a hot rock. It’s only as good as the help it provides.