Interfaces exist to enable interaction
Clarity is job #1
Conserve attention at all costs
Keep users in control
Direct manipulation is best
One primary action per screen
Keep secondary actions secondary
Provide a natural next step
Appearance follows behavior (aka form follows function)
Consistency matters
Strong visual hierarchies work best
Smart organization reduces cognitive load
Highlight, don't determine, with color
Progressive disclosure
Help people inline
A crucial moment: the zero state
Existing problems are most valuable
Great design is invisible
Build on other design disciplines
Interfaces exist to be used

Point in Passing _

Source: Principles of User Interface Design