Blog commenting is one of the best ways of getting links for your site and a common practice for website SEO. Unfortunately, this led to blogs being filled up with crappy comments that don't even contribute to what the blog is saying.
Because of this, a lot of webmasters configured their blogs to moderate their comments before posting them. In order to get your comments approved and, more importantly, your links published, here are tips to consider.
Avoid copy/pasting. Though it is very easy to just copy and paste your comments for easier, it's not a good idea doing this because it's going to be obvious that it's spammy. Generic comments are going to be very obvious. You could also set up a template but be sure to add a few words in that’s relevant to the topic.
Spare a few seconds to read the blog. You actually don't have to read the whole thing. A simple skim of the blog will allow you to get a grasp of what they're talking about. Aside from this, what you can do is quote a part of the blog itself or someone else's comment.
Check formatting. In order for links to count, they must appear in link format. Most blogs are capable of interpreting HTML format. Remember the "<a>" tag? Use that to your advantage when commenting. However, some other sites autoformat URLs into links so you won't be able to use a different anchor text for your link. Still, the link will still be beneficial.
Choose a relevant blog. Before you do decide to comment on a particular blog, be sure that the theme of the blog your commenting on is relevant to the site your promoting. If you own a site about computers and you are commenting on a sports site, the links you’ll be putting won’t amount to much. Even if you do get those comments posted, search engines may not put some weight in your links since the site you have links on are not relevant to your site.
Webmasters are particularly lenient when it comes to comments that actually add value to the content. So make sure that your comments contribute at least a little value to the blog.