Respect your user
This overlaps with the suggestions under Respect and persuade your reader.
Provide choices that validate the user's identity
Wherever possible, even if not directly provided on the form, provide space for the user to be descriptive about their identity.
- use inclusive options for gender, race, and disability status
- be cautious in using the "other" category to describe sensitive personal characteristics
Be thoughtful about when you ask for personal information
Your user may hesitate to provide personal information, such as address or birthdate, before they have become comfortable with the substantive questions in your interview. Consider asking for identifying information at the end.
But: it is OK to ask for the names of the user and the opposing early if it will allow you to ask more personalized questions. Consider saving the rest of the user's details for the end even in that circumstance.
Do not ask for personal information if you do not need it.