In the last 25 years, I have worked with Marketing organizations all over the world. I am still amazed about how they think about Influencer Marketing because they tend to take the old school PR approach and target individuals with the most reach. They target the Seth Godin, for example, who I worked closely with in the mid 90s. Even thought he is a genius, he will not help me sell a certain marketing automation service. He will not endorse without getting a very very big check. He will not help me figure out which lap top I should buy. (Maybe I should target Guy Kawsaki instead since he loves Macs).
When I was a consultant I built a whole business around a different type of marketing that focused on conversations and the connections between those people having the conversations. To do this, you focus first on the audiences tribe, which is basically a group of individuals with a common interest or hobby. A simple one would be stay at home dads. Or Mountain Bikers who live or bike in Tahoe. You don't focus on demographics (age, gender). These individual are engaged online and offline around certain subjects. Marketers can find them a number of ways such as analyzing trends or doing a keyword analysis that is a little different from SEO. For the stay-home at dads example, you list out and use the common terms this tribe uses. True influence is based on dyadic relationships which is based on two people and/or the smallest group possible. It focuses on the discussions and communications between these two people. (What it is not targeting someone with the largest followers??). It involves co-workers who might make a verbal recommendation at the office. It is based on time and the amount of time these individuals spend together and their emotional intensity in these relationships
But it takes takes time to reach out to all these people, right? Yes it does, so you don't. Instead you focus on the critical few relationships and the cluster that these relationships form around. See picture below. It color codes segments and the batches of people forming around these tribes.
You focus on user profiles and either build models to determine who to focus on or you randomly select a few with whom you can learn and test. You try and understand these conversations and how they go about making their purchasing decision. You try and identify what's the right motivation to get them to play 'telephone' - where they each tell one person about your service or product. You focus on the relationships and not the number of followers, etc.
This might seem like a time intensive activity, but in the long run you will save time. If you just cast a net wide and scoop everyone up into your marketing system, you will have very low engagement rates and you will loose the relationships among people that will actual reinforce customer loyalty.