Apply the four principles of human-centered design as a unified framework to tackle design challenges of any scale: focus on people in context, solve the right (root) problems, treat everything as a system, and work iteratively through small, simple interventions.
Distinguish between user-centered, people-centered, human-centered, and humanity-centered design, and apply the fifth principle of humanity-centered design (design with the community, not for it) because local people already understand their problems and have begun solving them.
Embody the designer's role as a mentor, facilitator, and resource-bringer rather than as an outside expert who has all the correct answers.
Apply an iterative, incremental modular design process to small and big challenges.
Reframe seemingly impossible global challenges (such as poverty, hunger, climate change, and gender inequality) as solvable through systems thinking and incremental modular design processes.
Make abstract design concepts like incremental modular design and systems thinking practical, both in everyday design work and when tackling complex socio-technical challenges. Understand that incremental modular design means muddling through continuous iterations, improvements, prototypes, and tests, rather than designing one complete solution from the beginning. Understand that a complete solution is often an illusion to begin with.
Tackle complex socio-technical challenges through small, low-risk interventions that accumulate community support and adapt to changing conditions.
Diagnose why the human mind struggles with complex systems (our wiring for immediate causality, single-loop reasoning, and short timescales) and design interventions that account for delayed, nonlinear, and multi-loop feedback.
Design for the deeply human need for instant feedback in any design solution.
Apply systems thinking to identify how curing one isolated symptom can leave the underlying problem intact or even make it worse.
Use the 5 Whys method to conduct root-cause analysis, avoid the trap of a single cause, and instead surface the multiple root causes typical of complex socio-technical problems.
Critique today's dominant success metrics, such as GDP, short-term shareholder profits, and the Milton Friedman doctrine, and articulate why companies must internalize the environmental and social costs they currently externalize.
Treat management as if they were "users" and speak the language of sales, margins, and spreadsheets.
Argue for design decisions in the financial terms executives use to evaluate them, in order to gain influence and a seat at the decision-making table.
Reframe failure as learning ("learn fast, learn frequently") and break big challenges into smaller bets that fail safely, and use the resulting insights as evidence of progress rather than setbacks.
Communicate complex ideas in clear, everyday language and apply Don's "in other words" test: When you find yourself paraphrasing, throw out the first version and keep the plain one.
Leverage the power of being a generalist to bridge specialists across disciplines, learn rapidly across new fields, and combine prior knowledge into entirely new disciplines, the way Don combined engineering, psychology, and cognitive science into UX.
Identify which of the four 21st-century design challenges is at stake and apply the distinct skill set each demands: Performance, meaning traditional craft; Systemic, meaning multi-disciplinary technology integration; Contextual, meaning co-design with local communities; or Global, meaning UN-scale socio-technical issues.
Take courage from controversy, recognize that meaningful change makes people uncomfortable, and understand that universal approval is usually a sign you're doing what everyone else is doing rather than changing the world.