So You Want To Be A Professional
First, go buy yourself some screenwriting software. I use Final Draft but there are others out there that you can get for free. Don't make the mistake that you can set your own margins in a word processor. Things go haywire and readers can spot those formatting issues right away.
Second, join a feedback group. And not some group where you submit ten pages and they assign parts to be acted out. Writers are not actors. Even if they bring in actors, what good is hearing ten pages of your script? You want dedicated writers like yourself. Writers who are willing to read an entire draft of a script and provide constructive notes. For me, it's a three step process. If you think something is not working, explain why and offer a solution for the problem. I know if you're not willing to think it through then it's just an opinion and everyone has one. I have been lucky enough to be part of a group of writers who are willing to support each other.
More to come on this...