Backlink education please?

Hello. I am trying to be a genius here. I have a customer, they already has some backlinks, they spend in google ads, they have shopify, and they have some seo already. Any suggestions on what tools I can use that are out there? currently he is using no tools. All I can think of is buying some backlinks? What would you do. He has ecommerce.

What does this customer pay you to do?