Roughly 75% of Search Engine Optimization is off-site work. This off-site work is about entirely composed of link building, which is highly important in the Google algorithm.
Some of the possible ways to build links include: social bookmarking, submitting to directories, writing and submitting articles and blog comments. Each of these different techniques is important, because Google expects to see a variety of link sources.
Blog comments are probably the fastest and easiest way to get links to your site. Make sure the blog you are commenting on is a do-follow, a good idea is to subscribe to fast blog finder, which does not provide no-follow blogs.
First off you do not want to look like spam because this will almost never get accepted. Read the post and make sure your comment adds to the content of the blog, share an experience or ask a question. Don’t just say “hey great blog” it is obvious that you have not read the blog and are just looking for an easy link.
Where it asks for your name put the keyword that you want to be found for. Where it asks for your site put the url of your website.
Not all of your blog comments will get accepted, because some people do not want you to use their blog for your gain. Other people however will appreciate your well thought out comment and happily accepted it, which will result in a link to help your site move up.