Keep it simple: In general, interfaces should use simple geometric forms, minimal contours, and a restricted color palette comprised primarily of less-saturated or neutral colors balanced with a few high contrast accent colors that emphasize important information. Typography should not vary widely in an interface.
Alan CooperJust how do I design if not with prototyping? An excellent question. The short answer is 'on paper.'
Alan CooperA powerful tool in the early stages of developing scenarios is to pretend the interface is magic. If your persona has goals and the product has magical powers to meet them, how simple could the interaction be? This kind of thinking is useful to help designers look outside the box.
Alan CooperComputers no longer interface with humans--they interact, and the interaction will become steadily deeper, more subtle, and more crucial to our collective sanity and ultimate survival.
Alan Cooper