The thing you’re working on is (I hope) very useful, and sure to make a difference if the right people use it.
But will they use it?
Which large or small, probably not-very-important improvements will make the thing more desirable?
What can you do to make it so that when people see / experience / hold the useful thing you’re making they don’t want to give it back?
That’s your iPhone* moment – when you’ll discover that those unimportant changes were actually very important indeed.
*I’ve never owned an iPhone, but people seem to like them.
See also:
Design matters: refrigerator control dial
Design Matters (2): badly designed Android Bluetooth menu
Design Matters (3): Ingenious board game tile holder and embodied memory
Design Matters (4): a recipe for trouble
Design Matters (5): the information architecture of a water dispenser
Design matters (6): Bosch hand-blender attachment
Design matters (7): Death by PowerPoint
Design Matters (8): Where’s that file?
Design Matters (9): Bruce Tognazzini’s First Principles of Interaction Design [Radio Edit]
A well designed paper bag from Waitrose
Postbox: good info
Design Singapore: Changi airport (1)
Structure Counts: Information Architecture reading list and who’s who
Steve Krug on Simplicity