When I'm struggling with a technical challenge in writing, I bang my head against the wall, write and rewrite and write again, and seek out books that have mastered said challenge.
The thought of a student asking me this question in a classroom, where I would have to improvise a coherent answer, is enough to make me retire. Story arc?!
I decided to ask some writers I admire what they try to figure out with their first drafts. What, I asked them, do you need to know before you begin? And what do you try to solve as you're working on that first draft?