If I learned one thing from directing Derelict (above all other films I've made) it's this:
Until a movie is made it doesn't have a voice. As the Director you are that voice. You must speak for the movie. The movie will tell you what it needs, a thought in your head, a whisper in your ear. You have to listen to it. People will try to shout over that voice. The will want to make their movie. But it's not their movie, the movie belongs to itself and you are the guardian of it until it can speak for itself. Your job as director is to be true to that voice and that vision.