Your comment must content positive approach ,no blogger will approve it if it does not have that . This is a bit difficult ,but keep on trying .On a blog of software comment that it was a really nice software
Do not comment often on a single blog
Guess Why do I ask so !I ask ,because that will simply burdden your personality over that blog .
Regularity is important in most of the things. But here you shoudn't be regular . Regular commenter does not get enough attraction of people .
Comment on your blog
Many bloggers believe hat commenting on own blog is scum .This really doesn't matter in many cases .Commenting on your blog may attract others to comment .
Use intesnsedebate or DISQUS
This may slown your blog . But ,this good for health of comments .That is why I have switched on intensedebate .and I will switch on DISQUS in short time .Hope you enjoyed this .
Practice your art here .(I mean do nice comments ! )