The first step in a successful e-mail marketing campaign is creating a database. The easiest way to do this would be by adding a newsletter subscription option to both your website and Facebook page. The easier to find, the more likely prospects will be to enter their details.
One initial auto responder email is fine but people don't want to be spammed with generic content, try to capture an audience using insightful and educational emails.
The longer your database builds, the more your conversion rate also builds, this is because the people who buy via email are likely to spend 100% more in their cart than those who don't. It also has a surprisingly higher conversion rate than social media so it should definitely be tapped in to.