The first thing a film director should do is bring a casting director on board to work closely with you in bringing in the right actors through the audition process, that will be able to bring the characters to life on screen.
While some film directors don’t like rehearsing scenes with the actors before the film begins shooting, but if this is the first time you are directing a film, it’s an extremely important process of filmmaking.
Because you will have all the kinks worked out in regards to the screenplay as well as the actors having a better understanding of what you as the film director are looking for when you call the action on the set.
For example, you are directing a scene, and you think everything was perfect and you want to move to the next scene, by asking the grip, gaffer, assistant camera person what they thought of the take will reassure you that the take was great and time to move on, or they might add something that you didn’t see and you can readjust and do another take.