I can understand a writer's impatience to get their baby out there in the "marketplace of ideas." All writers crave positive feedback and are sometimes even approaching desperation to break out of their lonely writer's life and see their work embraced by the many artist/collaborators in theatre and film and become a member of an artistic team that wants to bring a script to life. But that impatience can easily overrule good sense and, alas, scripts are continually sent out long before such a move should even be considered.
So my advice is this: When you think you've dotted the last "i" and crossed the last "t" on what you are convinced is your final polished and perfect draft of your play or screenplay, including fixing any and all formatting issues, having it carefully copy edited for typos, etc.--when you think you've reached that point after months and months of work--instead of immediately sending it out to those contests and festivals with their looming deadlines, and/or the agents or producers you have an even vague connection with who you are now certain will embrace your script, put it away for a month and forget all about it. Don't worry about missing a couple submission deadlines, even with the bigger, more significant venues. And don't pull it out and look at it at all in the interim. Allow yourself (or force yourself) to get some honest distance from it. Instead, start work on your next writing project and forget all about that "finished" script in the drawer.
If you do this, nine times out of ten when you do pull it out and give it a fresh read, "things" small and sometimes large will suddenly pop out at you that you totally missed earlier. Things that you now can see need more work. Things that competition readers and producers will spot right away. And in the vast majority of cases, those professionals on the receiving end of your submissions will only read your script one time and one time only. Rarely, if ever, will that later and stronger draft be picked up again by any of them.
I'm confident that if you take this advice, the script you actually finally do send out into the world will stand a much better shot of garnering serious attention and perhaps even eventually find it's way into production.
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I'm the Program Director of the low-residency MFA in Writing for Stage and Screen being offered by the New Hampshire Institute of Art. Our next residency runs January 3-11, 2015 and we are currently accepting applications. I'm also a playwright and screenwriter, producing partner in my production company Either/Or Films (The Sensation of Sight and Only Daughter), and a professional script consultant.