The process of getting something filmed, such as a movie, or a commercial, has a lot of *behind the scene* stuff, and storyboards are one of those things. When I first started doing them, they made perfect sense to me - it's simply doing visual storytelling, like a comic book, with multiple frames.
I grew up reading comic books. And from the great masters like Jack Kirby, I learned about staging action, showing continuity, long shots, close-ups. You know, just like in the movies. And any visual medium, from comics to film, relies on visual storytelling.
For me, it starts by looking at the script. For the project that I just started, I asked the director to give me specific instructions on what he would like for each storyboard frame, although the script already had that. I read both carefully.
It's amazing effective, going from a script to an animated storyboard. Even though the sketches are rough, everyone from the actors to the director gets a clearer idea of what to do. And that saves time, film, and mostly money.