Here are some tips by screenwriter Melissa Rosenberg for writers:
DON’T IGNORE OR RAIL AGAINST NOTES
There may a grain of truth in a pile of otherwise useless notes. Although some readers vent their frustrations on writers, they generally try to be helpful. The suggested fix may be wrong, but it may highlight a problem in your script.
DON’T THINK YOUR LAST DRAFT IS THE BEST
Screenplays are living, breathing, evolving beasts. Some executives believe that it takes two or three drafts before you truly find your story. Keep rewriting.
DON’T RUSH IT
Some writers like to “vomit out” a first draft so they can see something on the page. Take your time in crafting your story.
DON’T CLING TO FIRST IMPRESSIONS
The producer you hate may end up being your staunchest ally, and the sweet talking executive may be the one who dumps you first.
DON’T START A CRITIQUE WITHOUT OFFERING PRAISE
Very few scripts are totally without merit. Beginning your critique by summarizing the positive aspects of your scripts will make the screenwriter more amenable to your criticisms. If you hate something, offer a viable solution.
DON’T BURN BRIDGES, HOLD GRUDGES OR ANNOY PEOPLE
Most film communities, even Hollywood, are smaller and more incestuous than you think. Everyone knows someone who knows someone. This is a relationships business. If you don’t like someone, don’t work with them.
DON’T CLING ONTO SCENES, LINES, STORYLINES AND CHARACTERS
Every element of a screenplay is dispensable. You must learn to kill your babies for the greater good.
DON’T SAY THE FIRST THING THAT POPS INTO YOUR MIND
If you must, take a deep breath first. It just isn’t worth it and you are unlikely to change someone’s mind. Be diplomatic.
DON’T COMPLAIN ABOUT THE INDUSTRY
Nobody likes an incessant moaner. We all know things are tough, but studies show your complaining won’t help.
DON’T GIVE UP
Be resilient. Write for the sheer pleasure of creating art. I’ve lost count of the number of films that have been stuck in development hell for five to ten years. It’s the norm not the exception.

jurgen wolff
September 11, 2010
Great points. I would add, when somebody gives you a stupid comment, try to find out what problem they think they’re solving with that suggestion. Often their solution is stupid but they’re not wrong about the problem. Once you’ve identified that, you can come up with a better solution (while, of course, flattering them about their insight).
JG Sarantinos
September 11, 2010
Like many humans, readers can sense something is off in a script but can’t pinpoint the exact problem, so their comments appear uninformed. And of course, we need to be ever mindful of the artistic, temperemenal ego.