Mary, I think this is a good question! I have been wondering about the same thing. How should I write content for storyline, considering the fact that this software allows us to do more than we could for example in Articulate presenter (my case). In our process we make the instructors write the content, which will be voice over later to be used in the presentation. We are still doing that, but the content is written in a linear way (Instructors have in mind PowerPoint, and lecture type of narrative) So is us, the Instructional Designers who have to come up with ways of presenting that content visually.
I dont have that much of experience in storyline, so I am still looking for tips and suggestions on how to better design/write content for storyline as well.
One of the things is that maybe you can use lists of content more interactive, where you present the main point, and giv students the option to click on them to expand on more info. Also, you can build particular examples in separate layers, and give students the option to click on them to learn more about that topic in an applied example.
I would like to hear your experience, and tips if you have some.