Find blogs that your target customer visits and ask them if you can submit a blog post. Make sure it’s your best and don’t self promote. You’ll get a link to your app in your byline at the end of the post.
For every one blog you post on your own blog, try and write another one as a guest a blog. Some sites like Business2Community and Social Media Today also syndicate content from other bloggers. Submit your blog’s RSS feed to apply.