Screenwriting is an art.  Some will say, no, it is a skill; others will say it is neither.  It is true that with prose fiction writing the writer has almost unlimited range in how they can present their story.  The ability to get inside a character's head and reveal all kinds of facets to the aspects of that character.

The skill and art of screenwriting is the ability to express your story with emotion and drama while still conforming to the limiting structure of the screenplay itself.  Some screenwriters get stuck and feel so confined by the significant limitation of screenplay structure that they never evolve as a writer and ultimately give up. 

When I read an Aaron Sorkin, Scott Frank, Steven Zaillian or Coen Brothers script there’s voice and methodology to their writing that raptures me.  There's a "voice" a great writer develops, a style, the ability to use the limiting nature of screenwriting and still do it wonderfully, beautifully, and artistically.

There are five ways you can improve as a screenwriter that will help you become better at the craft but also reach the level of an artist of the craft.

1) When you are developing your screen story don't think in terms of just ideas, but concepts and theme.  A powerful, emotion screen story is one that has something to say in my opinion.  Even if the reader or viewer has a different emotional reaction to the story.  Think of the movies that you had an emotional response to, re-watch those and find the screenplay for it and study how the writer executed the structure and created a story that captured you like that.

2) Read screenplays of the greats and not so greats.  Today most movies that are popular the screenplay is available on the Internet.  If you can't find it there you can usually find it somewhere. Read, no devour as many as you can but don't just read, understand.  When reading for understanding you're paying attention to not just the story but HOW the writer is executing and presenting it, from the words they use to the structure all that is their "style" their "voice" as a writer and makes reading them so fun and exciting.

3) Yes watch movies, a lot of 'em. Understand how the words translate to the screen.  Film is the ultimate collaborative art.  A great movie indeed starts with a great screenplay but it does not end there.  It must have a great director, actors, cinematographer, editor and so forth.

4) You're probably thinking, Why hasn't he said, uh, WRITE!   Well, because it is obvious.  You better be writing.  A top agent once told me the great writers are writing daily, 5-7 hours.  Not sure now he came up with that, but yes, you need to be writing. Develop your craft, your style, your voice.  Find that grove that you can write in and create your art.  Have something to say.  Know how to say it that isn't heavy handed yet produces the desired emotional reaction or connection for the reader.

5) A wealth of knowledge to draw from is mandatory and that means you must experience things and that only happens by getting our there and living and exploring. By doing that you experience emotions and feelings and you see others doing the same and it gives you an insight into how to write good fiction because you are living and experiencing .

There you have it no excuses now to become a good, no great, screenwriter.... yeah if only it were that easy.

Good luck!