Authors should consider: what is your story's throughline? There are several different definitions of 'throughline.' Don't get bogged down in definitions. The point is: what is the central idea of your story? It needs to be evident in the first scene and in the last scene.
A story that peters out often starts with one central idea and then, somewhere in the middle, switches to another idea. This rarely works.
Personally, I tend to use the protagonist's main problem with its emotional component. Remember, one of your jobs as an author is to affect readers' emotions. Thus, scene one at least alludes to the protagonist's main problem and shows his/her/its accompanying emotions. The middle of the story is essentially the protagonist acting to solve the problem. The last scene is the solution to the problem with the accompanying emotions.
You don't have to do what I do, but you should have a throughline--some kind of consistency from the beginning to the end of your story.
Your central idea can be anything!
I look forward to reading what it is. Send us your story.