What are the best strategies for finding the perfect cast for a film production?

Obviously, the best route is to use an experienced Casting Director. If you go all the way back to the 70s, someone like Marion Dougherty was responsible for many of the stars who we still watch today. She would find them and offer them their first roles or their first starring roles. People like Hoffman, Pacino, Deniro, Streep, Close and more. In the absence of a great CD - and you should always at least TRY to get one no matter your budget/scale - your best bet is to search local theatre groups and online casting portals where actors upload their headshots and/or reels. But again, I know a Casting Director who got Marisa Tomei and Minnie Driver for a short so... shoot your shot!

More often than not these days, an actors initial audition will be a self-tape. You or your Casting Director will prepare characters breakdowns and audition sides (generally two scenes with some good back-and-forth, avoid action scenes as they won't offer much). If you have a Casting Director, he or she will send your list out to reps and those reps will (hopefully) curate their list of clients they think would fit each role. The upside of self-tapes is you will be able to see WAY more people. Then you shrink down the list of potential people and, if possible, bring those people in for in-person reads... this offers you or your Casting Director a chance to direct in the room and see how they handle adjustments.

Decisions regarding casting can differ depending on the project. On a short, for example, the director may have full control and carte blanche to cast whomever he or she wants. On a feature, the process will likely involve a discussion between the director and producers (and likely the studio or financier). In television, the showrunner will make the initial decision of who he or she likes. For network tv, the cast will then need to be approved by the network executives and in streaming, the cast will go through that approval process with the streamer or premium cable outlet.

Active Listening is one of the most important elements in gauging a performance for any director. When watching actors work, you should be looking for Truth, Honesty & Believability. The hardest task for most directors is KEEPING QUIET. You want to avoid over-intellectualizing and talking too much because you can numb your actors and it will encourage them to stay in their heads rather than working with their instincts. You want actors to react organically and not be thinking about the next line or when they are going to move in the scene. ? Because every actor knows his character’s “destiny,” the director has to work backwards to structure the behavior. You have to pace the performance to lead to the logical ending.

This is for the new filmmakers out there... Try to be open to possibilities. On almost every project I've worked on in 30 years in film and television, there has always been at least one actor who came in against "type" (usually put into the process by a smart Casting Director) and blew away the team... prompting them to alter the role for that actor... or simply let the actor "create" the character. Being open leaves room for surprise and surprise is very, very good. What is critical is to ask yourself whether the actor you're considering seems authentic. And if he or she can get where you want/need them to be in one scene, chances are they can nail the other scenes, too.