For starters, you can add an RSS link to your blog, which encourages blog readers who know what that means to subscribe to your blog in their news reader. You can also add an e-mail subscription link, which does the same thing except that readers will receive updates by e-mail. You can promote your blog through various social media websites. Search engine optimization techniques are always nice. And the list goes on.
One of my favorite ways to promote a blog, however, is with a newsletter. If you start a new blog and post to your blog three days a week, you can promote your new blog to your existing clients through your newsletter. This works especially well if you have a loyal list of clients and a good list of their e-mail addresses. There is no substitute for a responsive list!
Blogging has become the 21st century promotional tool. E-mail marketing has become the new century's direct mail marketing. You can combine these two marketing tactics into one very powerful marketing strategy that not only drives traffic to your blog, but encourages interaction and closes sales. I highly recommend a blog promotion newsletter.