The Rehearsal Is The Film
Most of the important directing work happens before the camera rolls. The rehearsal is not preparation for the film — it IS the film, happening in its most essential form: two people talking about what a character wants, why they want it, and what they are willing to do to get it.
Trust Is The Currency
An actor who trusts their director will take risks. An actor who does not trust their director will play it safe. Safe performances are invisible performances. The entire job of directing actors is creating the conditions in which an actor feels safe enough to be unsafe.
The Language Of Direction
Tell an actor to "be sadder" and you will get a performance of sadness. Tell an actor that their character just realized they will never see their mother again and you will get grief. Specificity is the language of directing.