10 years ago, companies began to acknowledge the need for a digital strategy, which drove the need for a search strategy, then a social media strategy, and today, an influencer marketing strategy.

The reasons for influencer marketing demand are because of cost-effectiveness, and because younger consumers are more apt to listen to certain influencers.

Leveraging 10 spokespeople is far more affordable than running one television ad, and with influencers, the only cost involved is their compensation and the legwork of helping them craft a message that speaks to the benefits of a service or product.

Former CMO of CNN and The Weather Channel, Scot Safon, told Setup that even B2B marketers are going this route, in lieu of the traditional trade show and print strategy.

"You used to mainly rely on trade magazines to get your B2B message across. And the advertisers and the trades were all close friends and renewed their annual deals almost automatically," said Safon. "Today, the trades are putting their energy in digital and social, clients are retiring or being replaced, and you just don't rely on trade print to build a brand."

"Honestly, you're more likely today to focus on listening to a influential person you trust and admire – and they are likely running a blog or commenting on social media every day. What does that mean for agencies? Suddenly, you need agencies who are experts at finding those people whose endorsement really matters," he added.

While targeting Millennials used to be all the rage, Safon believes that today, brands should be looking for agencies that can offer the right mix of people to influence your exact customers, no matter how old they are.

"If it's all Millennials, great. If it's a mix of people who love yoga, there'll be some 25-year-olds and some 50-year-olds, and people who are influential in that might not be influential in any other market," said Safon.

One way to look at an agency's influencer marketing skills is by comparing it to PR, a practice where publicists cultivate relationships with editors and journalists to whom they can pitch stories about their clients, and one that may ensure long-term success for influencer marketing.

When a marketer hires an agency, there's an expectation that they can provide insights that an insider wouldn't have otherwise discovered. The types of learnings that an influencer marketing agency can uncover are astounding, because what makes influencers influential is that they are vocal about their passion, whatever that may be.

"Today you can just be so specific – you have more information about more people than ever before, and you can see who they're following and reacting to. You still have mass-market challenges, but you really don't have mass-market solutions,” Safon said. “What used to be the mass-market campaign is probably going to be more effective conducted a person-by-person crusade. But at least you'll know how to find the exact right person, and you'll have a whole personal persuasion strategy, led by that influential."