Be flexible. As you write, the story’s plot might not unfold as you had planned. This is okay. Remember, the longer you’re immersed in the fictional world that you’ve created, the more your knowledge of your characters–their motivations, their thought processes, and their aspirations–will change; it will broaden. At times, this will require you to discard scenes that you had intended to include in your story. It will require you to alter others. You’ll also find that some scenes will be conceived of as you write. This is all okay; it’s good, actually.