Lots of “experts” have an opinion about how to create viral content.

But “there is so much misinformation out there,” says Jonah Berger, associate professor of marketing at Wharton and author of Contagious: Why Things Catch On. “So many social media gurus who have a theory, but don’t back it up with any data.”

So Jonah spent the last six years analyzing the data to see what makes people share content, and “it’s not luck and it’s not chance,” he says.

“There’s a science behind it,” says Jonah. “I can’t guarantee by following these principles you’ll be the next Gangnam Style, but I can guarantee that it will increase your batting average.”

In his Mixergy course, he shows you how to create buzz around your product or website. Here are three highlights from the course.

1. Get Inside Their Heads

What if people like your product, but no one’s buying?

That’s what happened to Kit Kat bars. “A few years ago sales were down,” says Jonah. “People liked the brand, but they weren’t thinking about it…It was just a problem that they never thought about.”

And someone has to think about a Kit Kat before they’ll actually buy one.

So how do you get customers to think about your product?

Create a trigger

Pair your product with a frequent and strong trigger.

For instance, Hershey’s created a campaign around Kit Kats and coffee. “First of all…there’s that alliteration,” says Jonah. “Second of all, you could imagine eating the two of them together, dipping a Kit Kat in coffee.”

And most importantly,”coffee is a frequent trigger in the environment,” he says. “People don’t just drink coffee once in awhile. They drink it every day, multiple times a day for some people. Pick a prevalent [trigger], one that comes up frequently in the environment.”

In fact, the trigger was so prevalent that sales for Kit Kats increased by $200 million.

2. Don’t Get Lost in the Crowd

crowdBarclay Prime steakhouse had a problem: How could they stand out in a sea of competitors?

“There are thousands of high-end steakhouses in the United States, dozens in every city, just like there are dozens of small businesses,” says Jonah. “And most close within a few years of opening because they can’t get enough traction.”

But Barclay Prime wouldn’t get traction from traditional advertising, since all of their competitors ran ads, too. And serving great steaks wouldn’t be enough, either. “Lots of restaurants have good entrees,” says Jonah.

So how did they finally get some buzz?

Violate expectations to get noticed

Barclay Prime served up a $100 sandwich.

Not only did customers rave about the truffle-covered, ribeye and lobster cheesesteak, but more importantly, they told their friends about it, who were curious to try it for themselves.

The media covered it, too, and “Barclay Prime [got] off the ground,” says Jonah. That was more than a decade ago, “and they’re still around today,” he says.

3. Make Them Feel Like Insiders

SmartBargains was one of the first sites to sell leftover merchandise at a discount. So for a long time, sales were strong.

But then similar websites started popping up, and sales flatlined. “Soon there started to be a number of competitors that are in the space, they’re somewhat similar, and it’s hard for [SmartBargains] to cut through the clutter,” says Jonah. “And so SmartBargains is sort of not doing very well.”

So how do you compete when you look like everyone else?

Add a red velvet rope

Make your customers part of an exclusive group of insiders.

For instance, SmartBargains saw that their special buyer program, which offered exclusive deals and perks like free shipping, was still wildly popular. “People loved this part of the site, people went nuts to be able to get access to things that not everyone else had,” says Jonah.

So SmartBargains created a new members-only site called RueLaLa, selling the same exact merchandise from SmartBargains. “And RueLaLa takes off,” says Jonah.

Why? Because “it feels exclusive,” he says. “It made people feel special, like they had something that not everyone else had access to, they can feel like they were in the know, they wanted to talk about it and share with others because it made them look good.”

Written by April Dykman. Production notes by Alex Champagne.