In my opinion, no single design is apt to be optimal for everyone.

Market segmentation s a natural result of the vast differences among people

No product is an island. A product is more than the product. It is a cohesive, integrated set of experiences. Think through all of the stages of a product or service - from initial intentions through final reflections, from first usage to help, service, and maintenance. Make them all work together seamlessly. That's systems thinking.

And to get real work experience, you need a job, and most jobs will require you to have had either real work experience or a graduate degree.

Behavioral design is all about feeling in control. Includes: usability, understanding, but also the feel.

When you have trouble with things—whether it's figuring out whether to push or pull a door or the arbitrary vagaries of the modern computer and electronics industries—it's not your fault. Don't blame yourself: blame the designer.

A good designer will actually design the company.