Start with the user: empathy-driven research will guide reveal the answers of the what, how, and why, ultimately defining the problem with clarity.
Design phase, simple as that: using design solution exercises (e.g. What's the worst solution to this problem?) and old-fashioned sketching to fuel divergent thinking.
Build a prototype. Test it. Learn from it. Repeat.
Product, service, message, system, etc. Time to get it out there.