This is the hard part. Here are a couple of things to keep in mind.  Have a clear call to action (CTA). If you want people to sign up, you have to ask them to. It could be as simple as some copy that says “Signup to our newsletter and get 10% off your next order!” CTA buttons help a lot. Include a big button on your signup form or popup with your CTA text on it.  Include a signup incentive. Offer a discount or free shipping in exchange for signups. Make this a part of your CTA like the example above.  Improve your traffic. If you’ve got a strong CTA and an exciting signup incentive, all you need is traffic.