One other way to send high ROI Emails (or) targeted Ad(FB/Google/IG) marketing campaigns would be to understand your customer interests. As you already have customer emails (or) leads i would suggest to try out this app(there's a free credit on it) to get your customer interests https://apps.shopify.com/customer-insights just from their emails. You will be able to get their full social profile from the email and alos their interests. Once you know your customer interests then you can segment them appropriately to run targeted email campaigns. This can also help you to target similar audience.