It is important to earn external links to get a good rank in Search Engine pages and you can do it in several ways. You need to be consistent and have patience when you are implementing different practices to earn external link. Yes, you can of course found sites or blogs that will allow you to live comment and can send you a back link. it works. Let me reveal you some more ideas.
Increase your activity in social media sites like Facebook, Twitter, Google Plus and join different group or circles and inform them about any changes or modifications you made in your own website. Try to stimulate their interest in your website by writing interesting blogs or articles related to your site and send them the link through the social media site. This may instigate them to explore your site and many will probably like to link back to your site. You can also ask them to do so, if they show interest in your site.
Some other ways: You can do social bookmarking, directory submission, article submission, guest blogging and blog comments.