Written by You comment online to share your thoughts and not to just leave a link back to your website. Social websites that allow you to leave a comment can also help blacklist your email at services like Akismet and others.
So, before you go ahead and comment. Make sure sure you follow the rules 
Rule number 1:
Only comment if you have something related to add. Remember that your comment only adds value if it is related to the topic. Also try to use keywords for the post in your comment. If for instance you would want to comment on this post, it would help to use the words “how to comment”.