"Find a good teacher."

• Take a screenwriting course. I took a couple from an excellent story editor and screenwriter who works in TV here in Canada. She, more than any of my previous instructors, helped me understand narrative structure and dramatic tension.
• One of the things I learned early on is that to complete anything, you have to be quite disciplined about making time to write. I developed a pattern now so that when I don't get to my keyboard, I feel as if I'm letting myself down. I've heard authors talk about writing as being an obsession. And I suppose it's become that for me.
• Find good teachers who can help you understand what makes a good story and can provide illuminating feedback on your work. Maybe even form a little support group of closet writers.