Believe me! If your website doesn't have any comment, you won't get much rank or traffic. People like to see your website in active with visitors and comments
write 5 comments on anything you choose: Google
+, twitter, blog,
forum, photo, or any website except adult or illegal content.
Here is what I'll do before I comment on your website:
1) I'll browse around your website
2) I'll understand your content first before make any comment
3) I'll make positive comment according to my opinion to the content
You can tell me which content you want me to comment on. Otherwise, I choose randomly.I don't make a long paragraph, but I'll make a decent words which no longer than 140 words.