I think Blog Comments is a best technique to increase your websites backlinks. Because once you comment on any blog and its approved by blogger, Then you get a permanant dofollow link from that website.Thats why i think Blog Commentv is best techniques in SEO.
There are many tehniques in SEO (search engine optimization). The best one is Social Book Marking , Forums , Article Submission or posting , blog posting , guest post. All techniques should be done systematically