- 5-10 minutes target. Under 5 feels like a quiz; over 15 feels like punishment. Pilot with 3 friendly customers first; measure completion rate.
- Progress bar visible. "Question 7 of 18". Hide it and abandonment spikes.
- Conversational headers. "Let's talk about your funnel" beats "Section 2 of 4".
- No accusatory framing. "How often does X happen?" not "Why doesn't X happen?".
- Mid-questionnaire micro-rewards. Every 5 questions, show a one-sentence insight: "Most respondents say the same about this question — here's why it matters."
- Optional fields are optional. Mark them so. Required everywhere kills completion.
Best practices: tone and length
5-10 minutes, conversational, never accusatory.