Advice on hiring a growth marketer.

I started a company during medical school creating supplements for certain eye conditions. I have the product created and selling in certain medical offices. I want to launch the product on Amazon; however, I am limited in my time during residency to give Amazon the proper attention. I want to initially compensate someone via equity and then actual payment within 3-6 months.
Does anyone have advice on how to approach this process, what to look for in a potential partner, and advice on structuring that deal?

I have not hired a partner previously and would love to hear how people have done similar things before.
Anything is appreciated!