Who is telling the story?
So many writers, especially at the beginning, make mistakes over point of view. They begin a short story or a novel telling the story through one character's eyes and then switch to the view of another character. And the reader, who is happily immersed in the story as 'told' by Character 1, is brought up short and the illusion is lost. You, as writer, has to decide 'who is telling the story?' and stick with it. Ok, you CAN change point of view but there has to be a clear signal...beginning another chapter, for example. You are taking your reader on a journey into your character's mind. Don;t risk them getting lost.