Ah yes, good question. My core approach is to use the biggest casting sites in LA – Breakdown Services (agents and managers see the Breakdown side; the actor-facing side is called Actors Access) and LA Casting. You can post both Union and Non-union projects on these sites, you just need to say which it is, along with other details about the project.
From the actor submissions on those sites, some combination of the director and I (depending on how much the director wants to be involved at this point) select about a dozen actors for each role to call in for an audition. I strongly prefer to hold in-person auditions because in addition to seeing an actor’s acting, you get a taste of their personality and how professional they are which is very important for how easy it will be to have them on the project and on set. There are low- and no-budget spaces to hold in-person auditions, so this is not a budget-breaker. At the in-person audition, I record the auditions because sometimes the actors run together by the end of the day and you need to re-watch the people you liked. If it’s difficult to schedule in-person auditions, you can alternatively invite the actors to submit self-tapes. They upload their videos to the casting site, and you can review them there. If there’s a role where we are struggling to decide between a few people, we can hold callbacks so we can see them again.
There are some exceptions to this process:
If you or I happen to know an actor who’s legitimately perfect for a role, by all means, we would reach out to them.
If there’s a role that is difficult to cast for some reason and we don’t find someone from the traditional casting sites, then I would distribute the character breakdown more broadly, for example to acting studios and on facebook acting pages.
I hope that’s helpful! And thank you for asking.