It’s one of the oldest and best-known facts of marketing: Nothing beats word-of-mouth.

And in 2016, word-of-mouth is no longer limited to talk over the back fence or around the water cooler. Thanks to social media, anyone can share their thoughts with hundreds or even thousands of people instantly.

Smart companies can use this to their advantage by turning their biggest online fans into brand ambassadors.

What’s a brand ambassador?

In the simplest terms, a brand ambassador is someone who advocates for a brand, says Nicholas Giustini, senior content strategist at Penna Powers.

A well-known and visible example is a celebrity endorsement. Fortunately for companies that don’t have the kind of money it takes to hire a big name to promote their products, there are other options in the age of social media. Anyone who is a fan of your brand and has a network of connections can become an ambassador for your brand.

“They’ve used the product, they’ve had a good experience with the product and they’re loyalists to the product,” says Melanie McBride, vice president of content and consumer engagement for Love Communications.

What is the value of a brand ambassador?

They lend their credibility to your brand. Good brand ambassadors are people who are already passionate about your products, and their sincerity shines through when they talk to their followers and fans about it, McBride says.

They’ll also be your defenders when people criticize your brand online. For example, Utah’s many multi-level marketing companies have legions of passionate customers and fans who are always willing to spring to their defense.

How do you find and keep brand ambassadors?

Be on the lookout for people who are already passionate about your brand and are already speaking about it. These are the people who will advocate for your brand with sincerity—and sincerity is what makes word-of-mouth such an effective marketing tool.

Monitor social media channels for people who have a lot of good things to say about your brand. You can also use one of a variety of listening dashboards—software or services that can monitor social media for mentions of your brand and alert you when they’re being discussed, Giustini says.

Develop a relationship with those genuine fans. Thank them for their support and make sure they know you value their opinion. Engage them in conversation. Reply when they comment on your posts. Consider offering them a sneak peek at upcoming products or events your company has in the works.

Bloggers often made good brand ambassadors, Giustini says. Bloggers can have large and devoted readership bases, and they’re trusted by their readers. Ask bloggers to try your products. If they like what you have to offer, they may become powerful fans and advocates of your brand.

You may want to compensate your brand ambassadors, but compensation doesn’t have to come in the form of money. Samples of your new products, tickets to your events or even just acknowledgement on your social media channels can do a lot to encourage your most ardent supporters to keep talking about you on social media.

Some companies are, by nature, more likely than others to elicit passionate support online. But even businesses that aren’t particularly “sexy” can make use of brand ambassadors and improve their support on social media, McBride says. “If you have a marketing plan that doesn’t include some level of brand ambassadors, you’re cutting yourself short of where you can go.”

Possible pitfalls

Don’t force it. “You have to be authentic,” McBride says. “If you are trying to solicit brand ambassadors who are not really sold on your product, they’ll think, ‘You’re just using me.’”

Don’t get caught up in the numbers.“Brands make assumptions based on how many likes and shares they get,” McBride says. “They believe that’s the sign of success, but they forget the people who are most engaged and active.”

Remember that you can’t control them. Brand ambassadors are not your direct employees, and they may not do or say what you want them to. We’ve all seen celebrity scandals that are followed immediately by a series of dropped endorsement deals. Be wise about who you engage with or they could end up doing damage to your brand.