News Letters are always underrated and are a great way to keep in touch with your clients, it shows you value there business and adds a very professional touch. A newsletter is a way to remind customers about you and your services or products, while providing useful information it also keeps the visibility of your brand constant.
Being the author of a newsletter can also help establish you as an authority on the topics on which you write. The more potential and current customers believe that you are knowledgeable about the products or services that you offer, the stronger the business relationship. If you are giving the information away for free, it also shows a willingness and desire to be helpful, and that you will provide excellent customer service.