When conducting search engine marketing, the quality and quantity of backlinks leading into your website provide the search engines something upon which to base your authority metric, bumping you up in the search results.
When making blog comments on sites that compliment your own, remember to mention your keywords 2-3 times, as well as your location (if pertinent.) Don’t be spammy. Make sure you are bringing value–or at the very least, validation–to the author’s blog.
Have patience: sometimes it takes a while for comments to be approved by the blog owners (if ever at all.)