Phase 2: The Screens

Sketch every screen, on paper or in any tool you like. For each, draw all four states plus first-run. Write the actual words: every button label, every error message, every empty state. Then draw the flow from arriving to completing the main task and count the clicks. Finally, show the sketches to somebody and ask them to point at where they would click to do the main thing. If they hesitate, fix the design now, while it costs nothing.