The most effective way of promoting a blog within the WordPress.COM community is to seek out other blogs in the same niche as our own blog and post meaningful comments to posts in them. Here is the link to the wordpress.com global tag pages. http://en.wordpress.com/tags/ There you will be able to locate blogs by category/tag that you can visit, read posts and leave comments on.
Here's a link to out Blog Promotion forum called Showcase > http://en.forums.wordpress.com/forum/showcase
Social networking tremendously expands the audience you can connect with. If you do not use social media like Twitter and and social networks like Facebook to promote your blog posts and blog, then you will find building a growing readership is more difficult as the audience you reach will be limited.
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