Copywriter service, what should I look for?

Hi everyone,

I am trying to improve my shopify store and would like to hire a copywriter on Fiver to boost my landing and product pages.

My problem is that I’m not an English native speaker and most of the gigs offer very similar services: engaging, SEO optimised content that converts. And I really don’t know how to asses it! How do you measure the SEO quality of a content piece? Do you recommend any tool? How does “engaging content that converts” looks like?

Do you have any recommendation of videos or articles that explain the basics of what I should look for?

Really appreciate your help!