There's no question that Warby Parker has become an e-commerce juggernaut: Since its founding in 2010, the eyewear startup has raised $215 million and opened 51 stores. Yet in the company's early days that happy outcome was by no means assured.

When co-founder and co-CEO Neil Blumenthal started to research the optical industry, he discovered that a single company--Luxottica--owned dozens of well-known brands, from Oakley and Persol to Pearle Vision and LensCrafters. Speaking onstage at Inc.'s GrowCo Conference in New Orleans on Wednesday, Blumenthal said he realized that he was going up against a Goliath. And he decided Warby Parker's weapon of choice would be branding. Here are three of the strategies the business used to build a powerful brand.

1. Details matter.

It wasn't that hard for Warby Parker's founders to decide on blue as the color for their logo. It's the best-liked color on the planet, Blumenthal said. But they knew it couldn't be any old blue. They chose the color of the feet of the blue-footed booby, a bird that lives in the Galapagos Islands. When the company was working on its branding, they put a picture of blue-footed boobies on their vision board. The boobie, they figured, was somewhat rare, and appears to be well-dressed. "They're sort of wearing a black-and white tuxedo, much like a penguin," Blumenthal said. And, of course, they have blue feet, which he described as adding "a little bit of flair, a little bit of quirk."

This may seem like overthinking both the bird and the color, but not to Blumenthal. "Brands are only powerful if they're real and authentic," he said. "Details matter. They create depth, and depth creates authenticity."

2. A little vulnerability goes a long way.

Just 24 hours after the official launch of the company--accompanied by coverage in GQ and Vogue--Warby Parker had to suspend its home try-on program. It had been allowing customers to try on five pairs of frames for five days for free. But it had run out of inventory. So customers asked if they could come to the Warby Parker offices to try on glasses.

The problem, Blumenthal related, was that he and his three co-founders didn't have an office. They were working out of Blumenthal's apartment with some customer service people they'd just hired.

So the partners decided to invite five people to come to the apartment and try on glasses. They knew it was going to be ridiculously awkward, with the glasses arranged on Blumenthal's dining room table. "Who walks into some stranger's apartment to buy glasses?" asked Blumenthal. But in a weird way, it worked. "We enabled people to take a peek behind the curtain," he said. "We showed our vulnerability. This is how brands can build relationships with customers."

3. Customer service is really marketing.

Blumenthal said there are essentially two ways for a company to look at customer service. One is that customer service is something that should be outsourced, and the cost minimized as much as possible. Blumenthal said Warby Parker takes the other approach: That customer service is a marketing channel that can drive incremental sales by making customers happy. Warby Parker's net promoter score (a commonly used measure of customer satisfaction) is about 84, he said. That's up there with icons such as Apple, and it's miles from most other optical stores, which Blumenthal said score in the 20s. Customer service, he said, "is an integral part of the entire strategy of the business."