This is where you will spend the bulk of your time as a well-crafted story is the whole point. A really great script or storyboard should make the production of your story very easy.
From: https://sites.google.com/site/digitalstorysite/process/create-script
From https://wikis.engrade.com/plottingashortstory
From https://edudigitalstorytelling.files.wordpress.com/2013/09/storycoaster-revisedblog.jpg
From http://www.mayaeilam.com/2012/01/01/the-shapes-of-stories-a-kurt-vonnegut-infographic/