From the book Script Tease by Dylan Callaghan:
Question: What guides you through a story if you don’t outline? is it character or a certain voice?
Diablo Cody: “I like to pick a theme. I know that sounds stupid. It’s not a super advanced technique. They pick a theme on Laverne and Shirley. I think about what the emotional core of the story is, what’s something I can play on across multiple story lines, and I go from there.”
P.S. There are many less accomplished screenwriters who would never reference the ’70s TV show Laverne & Shirley, but that’s part of why I call the Oscar-winning Juno screenwriter the Woman of Steel. And for what it’s worth, Laverne & Shirley was co-created by Garry Marshall. In the five years plus years of writing this blog, Marshall is the only person I have written a single month of posts about. (And that just happened to be the most viewed month of posts I’ve ever had.)
Related posts:
Theme=What Your Movie is Really About
Theme=Story’s Heart & Soul
Michael Arndt on Theme
Sidney Lumet on There
Garry Marshall—Survivor
“Emotional Catharsis”—Diablo Cody
Screenwriting from Iowa 
After reading your posts about Gary Marshall’s work I found his book “Wake Me When It’s Funny,” and I learned so many lessons from his career–plus I laughed a bunch!–Susan J.