It's who you know in the film industry. It's making friends, building contacts, doing good work. You'll see that it's such a small world.
For instance:
I played the antagonist in a short film last week --
With the director who hired me 4 years ago. In the short back then, there was a girl named Erica who had a very small part. But she was enthusiastic and lovely so she played the protagonist in this small project last week. (Bear with me here)
Erica and I discovered four years ago that her BFF Amber is the very same Amber in my high school drama club that I graduated with. Amber and I had done shows together. SMALL WORLD.
Fast forward again and the director needs to fill a small role.
So I forwarded my friend Eric's info to him.
I know Eric because I directed him in a scene in college. I was the first to hire him, actually.
It all goes around and it all comes around.
Make friends, build contacts, do good work, be kind, pay it forward, network.
The LA film world is a microcosm of people using their same favorites over and over again.