Whether you sketch it on a napkin or build an elaborate 3D animation in Maya, all (sane) directors will agree that some form of previsualization is a must before heading to the set. Storyboarding is one of the most accessible forms of previs, provided you can draw stick figures that have their arms and legs in the right place. (Although check out our previs series to discover how accessible modern 3D previsualization has become).
The RocketJump crew have done a great job of introducing the process of storyboarding, with some nice examples from major Hollywood blockbusters. Specifics of the process start around 1:30 into the video.
If you’re intimidated by a #2 pencil, Indy Mogul offers this video to reassure you that storyboarding is possible even for non-artists. Not as thorough as the RockJump vid above, but provides practical advice of exactly what information is essential to communicate in your storyboard frames.