I think this should be the #1 principle: "Define success in terms of your UI." Before you set out to design an interface you must decide what actions that inter

I think this should be the #1 principle: "Define success in terms of your UI." Before you set out to design an interface you must decide what actions that interface should expose and facilitate, and which of those actions constitute success. First you decide what the user should do - then you design around that. I know it sounds obvious and practical, but 9/10 companies I've worked for started designing the interface before they decided on what the interface should accomplish.