Literally billions of blog pages are around the Internet, and some of them have to be related to the subject served by your Web site. Many blogs allow visitors to respond; you might want to respond to messages and include a link to your site. However, two things to consider:
Avoid blog spamming: If you have nothing valid to say in response to a blog, don’t bother. Responses placed on blogs for the sole purpose of garnering links are known as blog spam, an obnoxious vandalism of the blogosphere.
Links in blogs are dropping in value: As a response to blog spam, the search engines introduced a new link-tag attribute, rel=”nofollow”. For instance, look at this link: <a href=”http://www.domain.com/” rel="nofollow">Visit My Cool Site</a>. When a search engine sees the nofollow attribute, it ignores the link. As more blogging systems begin coding all links in responses in this manner, the less valuable responding to blogs becomes.
How do you identify a Search Engine Robot?
Search engines send out what are called spiders, crawlers or robots to visit your site and gather web pages
About balancing the demand for your chosen keywords against the number of competing sites supplying relevant results
Another of the major problems that you might encounter in your SEO efforts is having your site content stolen