Process 

  • By now you should have a product require- ment document. Refer to it often: What it is you are building, exactly? Discipline yourself to use this guide. If your product starts to change radically, that's fine but that might mean a trip back to the Explore phase.
  • It's all process right now: Iterate, learn, im- prove, learn, optimize, and learn.
  • When you finish your first prototype, start working on your second, and third. Think in terms of success metrics: It's not how many prototypes, but what is the bar for the final one? And before that: What is the bar right now, for the next build?
  • Test for manufacturability. A good rule of thumb: By the time you reach your 3rd prototype, you should be starting to verify that it is actually buildable.