When people first signed up for your list, they were looking for specific information or an answer to their problem. As new marketers you tend to forget why someone originally signed up on your list, or you may change your message over the first few months.
Be as specific as possible when you are asking someone to opt in to your list. Find out exactly what they want and expect from you and then deliver it to them. Ask yourself who your target audience is and what your USP (unique selling proposition) will be.
As long as you stay focused on your niche and your market you will find that people want to hear from you on a regular basis and want to do business with you as well.