Aaron G. answered 08/20/19
Online/Social Media Marketing Guru, Photographer/Videographer
First, you need to figure out what the amount you can spend on marketing is, as well as how broadly you'd like to spend your time and money.
Then, look for influencers who are already sharing content that is similar to your product or that have personal brands that can easily be connected with your product.
You'll want to make sure that their average content is getting a significant number of interactions, and that their sponsored content is getting a comparable number of interactions compared to their average, non-sponsored content.
Many influencers will have set rates and/or will have a lot of data to share, so make sure to communicate with them in detail to understand if they will be a good fit, how professional they have been with you and other marketers, and if they fit in your budget.
If you're selling shoes, a person with shoe-focused videos that reach 500 views might be better for your brand and sales than a person with generic slice-of-life videos that reach 10,000 views. Receiving metrics and looking at their own personal channel(s) will help you understand who to reach out to or how much you should be paying.