Justin Mares talked about "Selling 40,000 Copies of your Self-Published Book (how I did it)".
He co-authored Traction, a book based on the idea that most start-ups fail because they don't get traction. How did they go about it? They did one-hour interviews on marketing and getting traction with founders and co-founders of several start-up companies. They had good relationships, which helped greatly in lining them up. BTW, the first person they interviewed was Jimmy Wales of Wikipedia, which made it much easier to get the other interviews.