Try showing a popup on exit or after a specific amount of time on page to get emails. If your blog is getting a lot of readers, but not generating a lot of emails, you should offer readers the opportunity to engage more fully with your content before they leave the page. This Wordstream case study showed that using an exit popup reduced bounce rate by over 60% and increased time on page by over 50%. SumoMe has a great tool for building your exit popup.