Read the Whole Blog Post: There are real reasons comments aren't approved by blog owners: they do not make sense or they do not contribute anything of value to the conversation sparked by the post itself. If you want your comments to make the cut be sure that, before you leave one behind, you read the whole blog post and understand what it is about. Your comment could be your opinion, a fact that you know about or just your analysis of the post, whatever may be the case, don't do it for the heck of it. You can get more back links if your comments get approved. 

Look for Blogs With Comments That Were Approved Recently: Commenting on inactive blogs isn't something that's worthwhile. Recent comments show that the blog is active and often visited. This just goes on to show that the blog isn't dormant and is receiving targeted traffic on a regular basis. Your goal is to have your comments published, but if the moderator isn't approving new comments, there's no point in commenting. Focusing on this one point can help you save a lot of time and actually get value out of your efforts.

Vague Comments Are Bad: Bloggers don't like seeing comments like "thanks" or "good post". This just shows the author that you weren't paying attention and they aren't going to approve that kind of comment. Until you add some value to your comment, there isn't any way that the comment you leave will be approved. Make sure that your comments are related completely to the topic at hand in the post that you are commenting under so that the blog author knows you've done the reading and understand. 

If you want to make the most of blog commenting and get your comments approved by the owners of do-follow blogs, keep the above tips in mind. It doesn't matter how effective your link building strategy is, blog commenting will only add more fuel to it if you do it the right way. So go ahead and start applying what you've learned here to make sure all you are able to gain valid backlinks from do-follow blogs.