Users aren't experts in solutions; they are experts in their own problems.
1The Mom Test
Named after the idea that even your mom shouldn't be able to lie to you about your business idea. Focus on the user's past actions, not their future intentions.
2Sample Size Matters
For interviews, 5-8 people is often enough to see a pattern. For surveys, you need statistical significance. Don't make big pivots based on a survey of 10 people.
3The Power of Silence
In an interview, silence is a tool. If you wait after a user finishes speaking, they will often add a 'hidden gem' of information that they were initially going to skip.
