Before you ever get started in production on your narrative digital video film it is important to get a sense of how the scenes and characters are going to play out, and so the actors have a chance to really connect with the roles they will be playing. Since films have multiple takes and are often shot out of order it is harder for an actor to maintain character development as they do in live theater. To help this you may want to use read-throughs and rehearsals before filming actually begins.
A read-through is where the entire cast and select crewmembers, such as the director and producer, sit and the entire script is read through out loud. This usually consists of the actors reading their lines in character and the director reading out the movements and locations descriptions. This does not have to be exceptionally formal, but try to get comments and questions addressed during this experience. If you have the time to do several read-throughs it can be helpful as an opportunity to refine the characters before shooting occurs.
The second step in this process is the rehearsal, which is an actual run-through of the scenes in the film. This is where you really define how the scene is going to play out, and you can coordinate the blocking and where the camera will be. The first rehearsals do not need to be on the set that you will be using to film, and you can use a large, open space instead. Try to let the actors do each scene once before giving direction, and then work with them until you feel pretty confident that the scene will go according to your vision. This is a great time for experimenting, so be open to suggestions from both the cast and crew. Try interacting with the actors as much as possible, looking at them from other angles and directing them very personally. This will help cement how you want to shoot the final scene.
Preparation for actual filming is an important part of the production process. Without knowing exactly what you want you cannot get something acceptable, so use tools like read-throughs and rehearsals for this purpose.