Although the thought of writing material that the market or industry prefers seems like a good idea at first, it has to be understood that by the time production takes place preferences may have changed. Writing scripts based on what you think others may want is almost never a good idea. To be original, writers, composers, and other artists must be able to think radically at the outset. After the basics are laid down and elaboration is under way, it is difficult or impossible to make a clich d idea into something better. You know if you are in good hands by how somebody writes.
Good writers have an ear for how people use language.
With most new writers, all the characters sound alike. You can tell by the density of pages sometimes. If the descriptions go on forever instead of one line or if the writer needs a half page of prose to describe the scene, generally speaking, you are in trouble. Not to mention that it can be really boring. If there is a single key to developing as a writer, it is to keep writing, and to keep submitting your writing to the reactions of an audience.