#GoodUXaphorisms 1: Make everything undoable, and for actions that are inevitably not undoable ask for confirmation with the default option cancelling the action.
This is especially important in mobile where accidental taps are frequent. But so many apps don't have undo at all, let alone having it in all the places it is necessary.
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko