When Lisa Mayock and Sophie Buhai created their first Vena Cava collection, they weren't planning to start a label. "We intended to have a barbecue in someone's backyard and show a few clothes that we had made," said Mayock last night at panel on entrepreneurship hosted by the Fashion Group International. "We made incredible invites in our friend's basement, and we delivered them ourselves. That naïve quality can really be an asset in a lot of ways, because you don't know what you're doing wrong, so you take a lot of risks."

Moderated by Karen Harvey, the panel featured Mayock and Buhai, Opening Ceremony co-founders Carol Lim and Humberto Leon, and Rent the Runway co-founders Jennifer Hyman and Jennifer Fleiss. Unsurprisingly, the three sets of partners are proponents of mixing friendship with business. Explained Leon of his relationship with Lim: "Someone asked us very recently why it is that we don’t seem stressed — it has to do with the fact that we're friends, and we work together as friends ... We’re close enough to know that after work we can go to dinner together and it’s after hours."

On starting a business from scratch:

Jennifer Fleiss, of Rent the Runway: When we started, we'd cold-call designers and we would ask to meet with them. And you can imagine when we first presented this idea to the designer community, they thought we were insane. Because we were saying, “we want to buy your clothing at wholesale, we want to rent it for 10 to 15 percent of the price at the same exact time that Neiman's and Saks have those designs.”

Carol Lim, Opening Ceremony: We didn't start it out by saying, “Let's plan these categories, let's hit this, let's hit that.” We just took this trip and said, “These are amazing things we've discovered, how do we bring this back? All of our friends would like this.”

On their most successful business decisions:

Sophie Buhai, of Vena Cava: Once you've developed a customer base, you have to give them newness but at the same time you have to give them the things that they loved from you. So we have certain ideas that we repeat every season. We always reference seventies silhouettes and thirties silhouettes and strong female characters from history, and people expect certain things from us that fall into that vein.

Fleiss: Our most popular silhouette is one shoulder. Our least popular color is black. People are renting the most editorial, fashion-forward styles because they're using this as a way to try something new ... 98 percent of our renters have rented brands they had never owned before.