One of the most important things about screenwriting is that once you have written your script, at some point you have to let others read it and evaluate it.
Yes, you ask if others, your friends or colleagues want to read - and then send them the script on an e-mail. After that you wait for their feedback.
This, of course, for a lot of people is much harder to do than you might think. It's not easy to let others judge what you have written, especially if you have worked on the script so hard.
It's not fun to think about the idea, that your friends, or whoever the readers are, wouldn't like your script. It's not an uplifting prospect to think that what you wrote isn't really that good.
Nevertheless, even though it might be difficult to let others read your script, you should give them a chance, so that together you can make the script hopefully a bit better.
For me it hasn't been that easy to let others read my stuff. I did let my friends read my first six scripts (Boston Legal, The Big Bang Theory), but once I started writing Modern Family specs, for some reason I didn't give them a chance to read.
This of course was not a good decision in any way. Even though it was emotionally easier for me to not let my friends review the scripts, there was really no other upside to it. I had nothing to win and everything to lose.
If there's one thing that you can take to the bank, it is that you're going to make mistakes. No matter how big or small they turn out to be, you're going to make them and you might not figure them out on your own.
For example, I make a lot of typos - and no matter how many times I read the script, I can't find them all. My latest script for example has a really silly typo in the end. How was I not able to notice that before I sent it to a competition?
Of course, typos are not the only kinds of mistakes that I tend to make. When you deal with three or four different storylines, it's very easy not to get the pacing right. You might get too married to some of your ideas so you don't know that there's a better way to do it too.
I mean, had I given my friends my second Modern Family spec to read, there's a good chance that they would have come up with a way to make it better- especially considering that I rushed it and didn't pay attention to it enough.
Or with my latest script that's now in a competition, perhaps they would have said that, 'hey, let's move that Boitano's "yes" a bit or let's write some additional lines. You never know. At least I won't.
In the end, it's me who's going to make that script good or bad, great or awful. At the same time, it's not a bad idea to give others a chance to read and a chance to make some suggestions too.