People buy when they feel that they have good reasons to do so. So, you need a strong value proposition (=great reasons for buying what you sell). If you don’t have it, you can’t be able to give people good reasons for buying. If you don’t know what—specifically—would make people see value in your offer, how could your email marketing (or any marketing) be effective?
Most people don't think of email as a lead- or contact-generating channel. But because people forward helpful emails to colleagues or friends, it can actually expand your database if you simply make forwarding or sharing email content easy for recipients. Include calls-to-action in your emails that make sharing an obvious choice for recipients, particularly with your most useful assets.

While email marketing ROI is higher than that of social media, you’d be remiss if you’re not combining both. While keeping your brand top of mind is an obvious benefit of using email and social, the crucial data you can derive from both enables you to hyper-personalize your messaging and content. This makes integrating both an integral part of your social media strategy and vice versa.