Mark Sigal – Nine Essential Truths for Entrepreneurial Success:

"Make sure that your product planning process is defined in a way that codifies specific use cases supported by clear workflows (in terms of click steps), backed by wireframes that express same. This is the ultimate 'rubber meets the road' moment when you realize that you are either talking the same language with your constituency of co-workers, customers, partners and investors, or not.

[…] In thinking about your product or service, always know what jobs you are focusing on, how they enable the outcome you are pledging to deliver and how they stick within the constraints your customer faces. "