The film director gives direction to the cast and crew and creates an overall vision through which a film eventually becomes realized. Directors need to be able to mediate differences in creative visions and stay in the boundaries of the film's budget. There are many pathways to becoming a film director. Some film directors started as screenwriters, cinematographers, film editors or actors. Other film directors have attended a film school. Directors use different approaches. Some outline a general plotline and let the actors improvise dialogue, while others control every aspect, and demand that the actors and crew follow instructions precisely. Some directors also write their own screenplays or collaborate on screenplays with long-standing writing partners. Some directors edit or appear in their films, or compose the music score for their films.