Most small businesses are scared to send out regular email marketing to their clients and customers. But it is the most important way to drive new business back to your website, being more important than Social Media & online advertising. Don't be afraid if you're email marketing isn't that good at first, or that people might unsubscribe. It's more important that you continue to practice and send out email marketing at least once per week.
If you're a small business, using Mailchimp.com is the best way to get started because it is so easy to use and learn, as long as you understand the basic principals of email marketing.