How do you choose good influencers to market your brand?

I've been selling on Shopify for a few months now, and want to move into influencer marketing, because some people swear by it. I have a few accounts in my niche that I like (some on Tiktok some on Instagram).

I was wondering if you guys had any recommendation on which statistics to look at, such as engagement rate, Idea, etc.

Or if you have some general 'red flags' to look out for that'd be helpful WordPress ...