An e-mail newsletter is the the most powerful way to keep in contact with readers and customers. It's also a sure-fire way to make any reader a potential buyer. If you find the opt-in rate of your website to be low, don't worry. Here are three ways to increase e-mail newsletter signups for your website. Engaging PicturesThis might seem like a no-brainer, but many marketers and business owners today still use images of people who are looking directly at the screen or off screen.