Promote your newsletter via two different channels/forms of content.
Hopefully, you've gotten your newsletter (or at least a link to subscribe) up and running!Now that you've got that in place, TALK about your newsletter in your channels. More than once. I put two as a minimum, but you can shoot for the moon if you really want.
Remember that you want to frame your newsletter as another product. Tell people what's in it for them if they sign up (more than updates and latest news - no one cares about updates and latest news, trust me) and what value they'll get. And make sure that you include a link or Call to Action (whichever is appropriate for the channel you're using) to guide people to sign up. You ALWAYS want to give instructions for how to access the products/offers you're talking about. Humans want to be told exactly what to do when it comes to marketing.
If you're struggling with what your newsletter will be about, we have a great workshop on FBCTV called Uncommon Email that you can watch.