When someone signs up to receive emails from you, they are saying that they are interested in what you are selling.   This is a privilege that you should not take lightly.  So when creating these emails, tell those potential customers something interesting and important.

Depending on how long your sales cycle happens to be, your subscribers expect emails at a reasonable time period.  If you send too many emails, then your customers will opt out and they will be gone for good.  In fact, in the course of a month or so, you will loose a percentage of those subscribers so plan on looking for new ones all the time.

You can put a link on your website and  when you create those links for  tell them what they will receive.  Will it be a newsletter or periodic tips and tricks or special discounts.  This will help to motivate them to sign up.  I would suggest to give them something free or signing up.

Of course their are laws involving sending commercial emails.  The CAN-SPAM Act of 2003 and the 2008 revisions is the name of the law.  You can go to ftc.gov to learn about the law and the 2008 revisions.  Their are parts of the law that states that you must provide a way for subscribers to opt out from receiving the emails.  Also your email must include your actual physical address.  You must also identify your business in the header of your email.  Their are many other parts of the law you need to learn and understand. The best way to get in line with the law is to use an email service company. Their are many email service companies that you can find so you can compare costs and services provided.

Email marketing is a good way to talk to your prospective customers one at a time and a way they can find your actual location.