Staying in touch with people is good.  Staying in touch with a purpose is even better.  Include a clear call to action in each newsletter you send, and make sure it is easy for your readers to follow through on the action you want them to take.  Want them to visit a page on your website?  Include a link to that page on your website – not just to the home page where your reader then has to figure out what you wanted them to see next.