Based on what I've read on TheQuestion, the best answers do at least some of the following:
- Review the latest studies on the topic in a way that anyone can understand, like this post by Jon Roozenbeek on media theories and what they can tell us about brainwashing. Or like Mohamed El Gendy's answer about why revolutions take place.
- Draw on the expert's own work and experience, like Professor of Architecture Sebastian Messer did in his post about what architecture tells us about society.
- Link to evidence and further reading, like this post by Cambridge sociologist Thomas Jeffrey Miley about the differences between Trump supporters and Brexiters.
- Use numbered lists, like this post about why polls failed to predict Brexit and Trump.
- Include pictures, like sociologist Alexandrina Vanke's explanation of how you can tell what social class you're in.
- Answer the question (!), like this short but very informative answer about why older people tend to be more conservative.
- Most importantly - the best answer is whatever the answerer wants it to be!