There are two ways of finding relevant blogs with whom you can exchange links. The first way is to conduct a blog search by submitting an article and then doing a search for your article to know who else is blogging on it. The second option is to perform a search on Google to find the right blogs.
If you decide on leaving blog comments to boost your SEO efforts, it is important to pick blogs that contain keyword rich and quality content that is similar to yours and also those that are not overloaded with too many comments. Posting comments on blogs that already have too many comments may not be very helpful as the blogger may or may not link back to you as you would hardly be noticed.
However, in order to get the bloggers attention to your comment or posting, you can ask thought provoking yet relevant questions on the subject in the blog. This will help you attract the attention of people towards the link pointing to your site and at the same time will catch the blog owner’s attention as well. This can lead to the owner also engaging in exchanging comments with you.
Blog commenting will be mutually beneficial to you as well as the blog site owner since there would be an exchange of words containing keywords and phrases that are generally searched by users. Besides, search engines also love keyword rich and fresh content.
The main advantage of blog commenting is that it does not cost you anything to post your comments on blogs and also it acts as a word of mouth publicity for you and establishes your credibility.