Many people say that a few days they had a page rank of three or four, and now do not have the rank at all. Why?
Now they do not have rank because they create a new post, and still no one leaves a comment on this post. Google works by counting links, as much back-links and comments you have, it means that people like your blog, and it have more value to Google. So, many people share comments or even pay for them.
The best way to find commentators is to join a social site for Bloggers, such as Mybloglog, BlogCatalog and other. When you join to this sites, find more friends and join in the various groups. Start to share comments with other people, the more comments you leave, you will get more comments.
When you leave comments, leave shorter comments, and always leave open the URL to your blog, or link to your blog in the signature. This also create a back-links to your blog.
When Google calculate, the number of back-links to your blog, and the number of comments on your blog, you'll have far more page rank, and Google will evaluate your blog more.
So, the more comments you leave, better for.