I believe that apart from technical skills a good filmmaker has to be highly educated in the issue of screenwriting. The magic of storytelling always has a powerful impact on personality and usually defines the general impression from a film. Highly cost visual effects or remarkable music can`t replace the soul of a movie - the plot. To my mind, the biggest treasure of every picture is hidden in the hero's dialogues and monologues. These expressions contain an inner voice of the director, hence - the dominant message and heritage left for judging.
In this case, it`s very important to train your writing skills to be ready to produce a significant scenario one day. Accidentally, found an interesting resource with practical tips for creative writing. Hope, it will help you to build a story of your dream and complete an outstanding masterpiece.
Thank you for such detailed review and interesting thoughts! It makes me think on different topics from another perspective.