Dont worry if moderation is turned on. Goto blogsearch . google . com click on any of the blog. The page that gets opened is the latest and hot topic. Read the post carefully, do some google on that post and find out what you can write. For e.g. someone writing about Taylor Swift with Kayne today, read other comments, do some google before you post. The blog owner will be happy to see intelligent comments. Write intelligently not just plain vanilla comments like "I like your post blah blah". I have tried it and so far my success rate has been 95% with my postings. And my backlinks are getting stronger day by day. I dont blast, but do around 10 postings a day in 1 hour. It is fun as well.