Without customers, you don't have a business ... and without steady growth, you can't build a business.

Obvious, right? What's not so obvious is how to pull those things off.

So let's ask a guy who knows: Steve Conine, a serial entrepreneur and co-founder of Wayfair.com, the e-commerce business started in his spare bedroom that is now a $3.3 billion company with over eight million active customers.

That's right. Eight million active customers.

Not too shabby.

You co-founded the company with Niraj Shah. What advice do you have for entrepreneurs who are thinking of starting a business with a partner?

In a lot of ways, a business partnership is like a marriage. When you work together, you go through some moments when things are going really well and you also experience challenges -- all of that enhances the partnership over time.

The more time Niraj and I spent working together, the more we both started to gravitate toward our natural interests and strengths -- and we recognized that we didn't have to excel at the same skills. Niraj is more interested in the overarching business strategy, whereas I'm more excited by the technology.

Our strengths complement each other really well.

Early on you created a number of stand-alone sites instead of building out one central platform. Would you do it differently today?

I credit much of our success to the fact that we created stand-alone sites before building one central platform. Our many sites provided us with a fertile environment to run a variety of experiments.

To build a durable brand, you have to have a very consistent experience -- that's one thing people tend to miss. With many separate sites we could easily experiment and test different approaches while minimizing potential negative outcomes, and it also allowed us to more quickly tune our systems until we could deliver a highly consistent experience across all sites.

Had we launched one brand in 2002, the customer experience would have varied dramatically depending on what they ordered. It would have been a lot harder to be universally loved by customers.

Talk about scaling. Rapid growth is great, but also creates a huge challenge.

One of the biggest challenges many fast-growing companies face is maintaining a certain culture amid rapid expansion. For us, having an entrepreneurial culture is part of our DNA -- in fact, we specifically hire individuals who are willing to be creative and think outside the box to solve problems or come up with new initiatives.

Since day one we've deliberately taken steps to maintain that spirit and mentality among our employees, and it's benefited the business. As many startups scale, they can lose sight of the culture they had when they first started their business -- but it is really important to Niraj and me that we keep the culture consistent as we continue to grow.

Once you reach a certain size, you become more of the hunted than the hunter. Was there a point when your strategy needed to change?

You can never let your guard down no matter how fast you grow, but it's true that your competitive landscape evolves over time.

Another area this impacts is recruiting. We are definitely a more sought-after employer now than we were 10 years ago, but we're also competing for talent with bigger tech names -- and we've shifted our approach accordingly.

You have approximately 7,000 suppliers. How do you deal with the complexity of servicing not just millions of customers but thousands of suppliers and products?

We didn't always have 7,000 suppliers. When we were just two guys in a room, we created a system that serviced the problems we were dealing with at that time.

As the business grew, we automated systems that were once manual, and they are still getting a little bit better every day. It's been a gradual process that we've been able to perfect over time as we continue to scale the business.

Do you feel your company's culture was developed over time, or was it intentional from the beginning? What do you know now about culture that you wish you had known?

Wayfair's culture is very intentional. This is the third business Niraj and I have started together, so we were very deliberate in shaping our culture.

I think the companies that stay true to their culture are often the ones that are still managed by the people who started them. When founders are focused on an exit strategy, the incentives are different. The founders who stick around really care about the company, and the culture is very important to them.

Say I'm hoping to start a company, and you have five minutes to give me advice. What three or four things would you most want to tell me?

The number one piece of advice I would give you is to assume your startup is the last thing you're going to do in your life. You need to be fully invested in your idea, and be doing it because you love it.

My second piece of advice is to take a long view, and don't have a preconceived notion or path of how things will be.

Finally, be confident and bet on yourself. There will be times in the history of your business where someone will come along and offer to make your situation seem safer or less risky. You might be tempted, but I suggest that you think hard about those decisions, because you can often do more with your own grit than you can with the soft cushiness that comes along with safety nets.

The more safety nets you surround yourself with, the more difficult it becomes to move fast.