It's tempting to think you're capable of catching all your errors but no one is
perfect. That's why you may want to consider getting someone you know to read
your script.
You can hire a professional script reader to review it and give you notes. But most charge over $200
for it. I
offer this review service for $85, or you can ask a friend to do it for free (well
maybe you'll have to take them out to dinner).
To make it easy for your friend to give you the feedback you need to edit your
script by giving them a list of questions to answer as they read your script.
Your friend not knowing anything about screenwriting is the perfect reader
because he'll just tell you want he sees not what you want him to see. No matter
how meticulous you have been you may have missed something that is clogging up
the clarity of your script and because you're so close to it you may have missed
it entirely. But someone who knows nothing about your script goes into it with
fresh eyes. All they see is what is on the page - not anything you have in your
mind which you forgot to put into the script. So if anything important is
missing your friend will point it out to you by telling you which parts were not
immediately clear to him on first reading.