I've had numerous readers, both from my writers/producer's circle that I trust and a few new people, read my new horror script and gotten all kinds of notes.
So, let's talk about what kinds of notes work and what kinds of notes don't ever work, so YOU, as a writer, know how to decide which to take seriously and which to take with big grains of salt, or even dismiss completely.
Ultimately, there are only 2 kinds of notes you can get:
1. The notes from people who read your script, looking at it from purely a reader's point of view. What worked and what didn't in this story based on what it IS. And based on that, what they see as things that can help make it better based on what YOU, as the writer, are trying to do. Helping you with YOUR story, told your way.
2. Notes from people who read it and say to themselves all the way through "No. I would do it this way" essentially making it THEIR script, their story based on your premise, and not based on what YOU are trying to do with it. Looking AROUND your story and wanting you to change it to suit their point of view. They don't read it to take in your story your way at all, instead thrusting themselves into it as the potential writer.
Obviously, number 1 is the best kind of notes. Number 2? Mostly notes that fit what you think of as number 2.
You want to be a valuable note giver? Take YOURSELF out of the process. I know that sounds weird, but it's really not. You need to remove your ego and seriously only look at the intentions of the writer. What are they trying to do with this story? What are their aims? What notes can you give them to help them achieve their goals with the script? Not what your goals would be. Believe me, there is a HUGE difference.
I got some wonderful notes from some people. Just fabulous. Small character things that would help define them more. Some asking me to clarify certain things they found a bit unclear. I got that same note on one scene from three good readers. That's something I addressed because it clearly was a problem. I was too close to it to see it and because it was clear to me doesn't mean it's clear to readers. Those are the best kinds of notes.
I got notes from those in the first category about pace, about setting, about clarity of character motivations based on who I wanted my characters to be, about character names being too close to each other so there was confusion about who was doing what. These are GREAT notes. Things I changed in subsequent versions because they made the script better.
Second category? Not so much. Changes based on their political viewpoints (there are no politics in the script, it's a damn horror movie meant to entertain), so that it would make a political statement they'd like to make. Changes to my story that would make it THEIR story taking it where I had zero intentions of having it go, and if they actually read it without putting themselves into it, they would see that. Changes to character motivation that make it a different story than the one I wanted to tell. The list goes on. Notes that had nothing to do with what I was aiming for, just what THEY would aim for. These are not great notes.
Think about it. What kinds of notes do YOU value? What kinds of notes do you want?
Do you want notes from someone who would take your idea and make it their own or from someone who wants your script to be the best it can be based on what you're doing with YOUR story?
This goes the same way if you're the one giving notes. Can you read someone else's work and see it for what the writer intended or only through your own creative lens?
This is the very reason, when I am asked to pitch my take on a script from a producer for a rewrite job, that my first question to them is, "Why did you option this script? What is it about this script that made you think it was something you'd want to make?"
Then, I take their answer and tailor my notes to that point of view. To give my rewrite notes based on what the original writer's intentions with this premise and story were, because 99% of the time that's what producers liked, just not the execution of those intentions.
That's when I give my notes to improve or change what's there, not to change it and make it my own original work. Are there times I held ideas back because it made it another script, my script? Yep. If asked, and I have been asked, "What would YOU do if it was your script?", then I give those ideas, but very, very carefully.
I know of too many writers who have been fired from projects because they couldn't rein in their own ego and had to write something "their way" rather than creatively staying within what made the producers buy it in the first place.
This isn't always easy, because it's hard not to take something and try to make it your own. It's conscious work. To be aware, in the case of writing assignments or just giving notes to a friend, that it's not your script, but someone's hard work you are helping to improve, if you can. Improve, based on what they tried to do with that particular story.
Have I been guilty of doing this? Oh yeah. Are you kidding? Sure, when I first started out. Every writer has at some point. But you realize it's not constructive and also can lose job opportunities for you and you adjust your thinking. Or you don't and eventually can't understand why no one asks you for notes anymore.