There are an infinite number of stories to tell. How do you choose where to place your story lens?
Which character(s) do you decide to focus on? Writing is after-all really just a series of choices.
Firstly, I must tell you that you are not creating the story, it already exists, it is already within you.
Original storytelling invites the writer(s) to journey inward, to search and discover, to chip away everything that is not the story.
Decisions are based on this internal journey, as you discover and find, walking down paths that you have never walked down before.