Blog commenting is the best way to improve your website ranking in white hat SEO technique.
Blog Commenting is considered a useful way to build links and it is an SEO technique used for getting traffic , building of links and helping to get ranks.
Blog commenting is the another SEO technique to build links and to get direct traffic for your website. Writing Comments is also the great way to advertise about your website.
Blog commenting is a way to interact with other people with whom you share the same view or different view about a topic. From an SEO perspective, blog commenting should not be done to influence ranking,it should be done as part of building a community. So either its has a do-follow or no-follow attribute is secondary. What is important is, you have something meaningful to contribute to the subject at hand.
There are lot of benefits of blog commenting, whether it's for socializing purposes or a method to bring more popularity to a site. Blogs have long ago been recognized as a good way to earn money online - but only if they are properly optimized to attract as many people as possible. This can be done in a variety of ways from having the site indexed, providing quality content or commenting in other blogs.