Popup marketing is an art that can take time to master. Let’s get you started with some basic advice.
Think Like a User
This is a very general recommendation. Most marketers make the mistake of thinking like marketers when they approach popup marketing. Their only focus is on the absolute number of emails they collect. To do so, they will limit the closing options, design gigantic popups, or display the popup on every other page the user visits. The problem with this approach is that it often ignores basic user experience principles and angers visitors.
So before designing your popup, put yourself in your users’ shoes. How would you feel if you were to see your popup?

Source
Add Strong Incentives
Again, most online shoppers are exposed to a lot of marketing messages. To make sure your popup stands out and your visitors engage with it, you need a strong incentive. Again, what would convince you to take a survey or share your email address as a user? Is it a coupon? A chance to win a product? What kind of content would you like to receive by email?
Finding answers to these questions will help you identify your visitors’ triggers.

Source: saucony.com
Separate Desktop and Mobile
Designing websites for mobile and desktop is different. The same is true for popups. Users interact with forms differently when they’re using a touch device.
Google also shared some specific guidelines regarding mobile popups. If you ignore them, you’re headed for trouble.

A mobile popup on Gshock.com
Leverage the Context
When users browse your store, they leave a lot of signs of what they intend to do. If they move their mouse upwards, they’re likely to reach for the top of the screen to close your website and leave. If they’ve added items to their cart, chances are they intend to buy from you soon. If they’ve already been on your website recently, these chances are increased.
We recommend you leverage these signs to improve your popup targeting and optimize your performance.

A popup on Bestowe.com displayed on exit on the cart page
Build a Strategy That’s Yours
We could list a lot more recommendations. But the truth is that each situation is unique. What worked for a different BigCommerce user wouldn’t necessarily work for you. How do we know? Because we do a lot of tests with our users. And in most cases, what we found with client A doesn’t always apply to client B. That’s why we recommend you test your popup timing, position, wording and incentives.