The summary.
PRIMARY ACTIONS BELONG LOW AND CENTRAL, WITHIN THUMB REACH
Not in top corners. And hover does not exist — anything revealed only on hover is unreachable.
Always provide a visible alternative to a gesture. Undiscoverable gestures are undiscovered.
KEEP IMPORTANT DESTINATIONS OUT OF A DRAWER
Content behind one is used considerably less.
Ensure back behaves predictably from every entry point, including notifications and links.
SET KEYBOARD TYPES AND AUTOCOMPLETE HINTS ON EVERY FIELD
They let the system fill names, addresses and one-time codes, saving substantial typing and errors.
And ensure the focused field is not hidden behind the keyboard — one of the commonest mobile faults.
DESIGN FOR INTERRUPTION AND RESUMPTION
Any task may be abandoned partway. Save continuously, restore position, and never lose entered data.
Prefer undo to confirmation — confirmations are dismissed reflexively.
CHECK CONTRAST FOR SUNLIGHT AND TEST AT THE LARGEST FONT SIZE
Fixed-height containers and single-line labels are what break.
TREAT OFFLINE AS A NORMAL STATE, NOT AN ERROR
Queue actions, show what is pending, and measure data consumed. Every byte is paid for by the user.
