The details that separate good from adequate.
WHAT PEOPLE NOTICE WITHOUT KNOWING
Inconsistent spacing Misalignment Mixed corner radii Varying icon weights Slightly different shades of the same colour
WHAT THOSE COMMUNICATE
Carelessness.
WHAT TO AUDIT
Every distinct value in use: sizes, colours, spacings, radii.
WHAT TO REDUCE THEM TO
A small defined set.
WHAT ELSE MATTERS
Optical adjustment: things that measure equal sometimes look unequal.
Trust your eye over the measurement.
WHAT TO CHECK
Text against its container: equal-looking padding, not equal-measuring
Icons against text: aligned to the text, not the box
WHAT TO REFINE LAST
Shadows, borders and effects.
WHAT TO USE THEM FOR
Indicating elevation or separation, subtly.
WHAT TO AVOID
Heavy shadows Borders everywhere Effects that serve nothing
WHAT TO DO BEFORE CALLING SOMETHING FINISHED
Review it at actual size, on the device people will use.