That constant roar of customer feedback? Be thankful for it. It holds all the secrets to your success, if you learn how to read the signs. Listen to what users say, sure. But also watch what they do and interpret what they need. Eventbrite's Julia Hartz embodies this principle. She believes passionately in learning from her customers, and has made rapid response to user feedback the driving force behind Eventbrite’s strategy — as it grew from a simple ticketing app to a full-service platform for event creators, offering everything from ticket sales to custom-made RFID readers.