Doing Previz allows a director of a production to supervise and experiment with different staging and art direction options for a project. It helps with budget and efficiency. It can provide accurate details of how to use the camera on the set. I think Previz is a more physically accurate version of the 2d storyboard.
Rule of third
The rule of thirds in photography is a guideline that places the subject in the left or right third of an image, leaving the other two thirds more open. It divides a photo into nine equal parts, split by two equally spaced horizontal and vertical lines. I think it helps a lot with the aesthetics of a movie.
Bringing the world to your scenes
I think the most important thing when it comes to world building is research. Imagination is important as well. It is fun to create and bring exotic creatures, rich political histories in a story.