What do you learn after four IPOs held in very different business cycles — and what if you're still trying to raise money privately? Gokul Rajaram, product engineering lead at Square, participated in that firm's IPO roadshow late last year. Previously he was product director for ads at Facebook, and a product director for AdSense at Google. He talks to USA TODAY's Laura Mandaro and Array Ventures' Shruti Gandhi about these questions, his blue shoes and the "Kombucha rule".