Five people, one afternoon
Give five people a realistic task with your prototype and watch quietly. Note where they hesitate, misread or give up. Three people stumbling at the same point is a pattern; fix it before you test anything else.
Ask better questions
- "What do you expect to happen if you press this?" — not "Is this clear?"
- "What would you do next?" — not "Do you like it?"
- "What is missing?" — people are better at spotting gaps than judging beauty.
Giving critique
Tie every comment back to the brief: "The brief says older readers — this text size will be hard for them" is useful; "I don't like the font" is not. Say what works as well as what does not, so it survives the next round.