You might think email marketing is old school and inefficient way to approach customers, and you will be half right. Yes, it is kind of old school-ish, but inefficient - not a chance.
So, it is probably safe to assume that you have already built a decent mailing list, by adding a mail signup in your website and social media profiles. What you need to do next is to send a welcome email. Don't try to sell things right up - you don't want to come off as desperate but you need to make them interested in you (it is kind of like when you want to ask a girl out:) ). How to do it? Well, here are some tips:
1. Make them recognize - the first thing people look at when they receive an email is the "from" line. The need to know who is it from before even know what's it about (the "subject" line). Make it easy to recognize you - write your company's name or the name of the person the people subscribed to. Everything else will confuse them and they will trash the letter.
2. Remind the subscription - most people subscribe for a mails and forget about the subscription on the next day (at best). The welcome mail is the perfect opportunity to remind them how they subscribed for your mails (if they don't remember - they will trash it immediately, or worse - mark it as spam).
3. Be original - have some fun, stay away from the monotony, add some personality to your email.
4. Brand the email - use your company's colors - it shows you are legit. Be consistent in the look of your emails - the easiest way to make the customer recall your company and subscribing to it.
5. Link to usefull places - by "useful places" I mean pages of your website and social media profiles. You have a Facebook fan-page? Good, throw a link to it in there. You have a page with prices or FAQ page on your website? Awesome, link to them.
6. Say when - make sure there is a sentence in the email which tells the reader how often they will receive mails from you (once a week, once a month etc.)