There are so many good methods for seo, social bookmarking, social networking, article directory, guest blog...The most important thing you should keep in mind is that write high quality unique content that many people will like and give backlinks to your site. For blog commenting, it's the best choice to find those relative popular blogs in your niche. If you comment on these blogs, you will get a lot of targeted visitors to your site if your comment is interesting and attractive enough. And if the blog is dofollow, you will get a good dofollow backlink to your site. Referring to blog, another more effective method is guest blogging. You can find someone who accept guest post, then write unique article for him and ask for a backlink. It's pretty easy to find those who want guest post from others. Just google "guest post","submit guest post","add article","submit article","guest bloggers wanted" and so on. Not only can you submit your article to blogs, but also you can submit to article directories and any popular websites in your niche.