When you submit a comment on other people’s blog, you are usually asked to provide your name, email address, URL and comment text itself. You can use your keyword anchor text as your name. When your comment is posted, your URL becomes attached to your keywords.
Be sure to write something useful in the comment section, so it doesn’t look like 100% spam. Don’t post 2 word crap like "great post", rather try to contribute to what the initial post was about. Post a comment only if you have something of value to add to the discussion and not just to get links. Your comment will be pending for approval and blog owners are much more likely to approve your comment if it is relevant. Remember, the only cost of your new backlink is a comment. So, take a few moments to write a meaningful comment.
After the comment is submitted, add a short user note for the blog something like "Posted" or "Awaiting moderation". You will want to return to the blogs where your comment was pending for approval later and check the comment status.
If you liked the blog you commented on, do not forget to submit it to social media sites using Share It button. This will give more exposure to the blog posts that you have commented on and increase traffic to them. Some of the traffic will trickle down to you, making your comment more impactful.