When you are marketing to your list you will want to make a schedule for what types of messages you want to send. In the beginning I recommend setting up three messages at a time. One should be a helpful tip or other information on your niche topic. The next one can be a link to an article or a blog post you have written that is about a topic that would be of interest to your prospect. They may not be aware that you have a blog or are writing articles, so this is an excellent way to share that with them. The third message can be more promotional, where you are telling them about an affiliate product they may be interested in, or one of your products or services.
The first two emails earn you the right to send the third one. My experience has been that my list appreciates my free content and information so much, they are excited when I share something they can purchase. Make a schedule for the next month, sending an email every three days or so. If you mail about 9 or 10 times during the month, three of the messages can easily promote something for sale. This is a nice mix and will build trust with your people while also giving you an opportunity to monetize your online business.