1. What’s the hardest part about [problem context] ?
2. Can you tell me about the last time that happened?
3. Why was that hard?
4. What, if anything, have you done to solve that problem?
5. What don’t you love about the solutions you’ve tried?

From : http://customerdevlabs.com/2013/11/05/how-i-interview-customers/

You should also subscribe to SWNEXT Youtube channel!

More generally speaking some excellent videos for Startups on « Google / tools for entrepreneurs«