It takes a lot of work and dedication to make a blog successful. But most blogs will never be THAT successful. You have to do it because you like doing it and not for the traffic and fame.
Most people do not leave comments. Many just read.
If you have a WordPress.COM blog, link your site url starting with http on your profile so your name is clickable on the forum here and other WordPress.com blogs.
Go to other similiar type blogs and forums with a link back to your blog on your username.
Use good tags or categories, no more than 12, and they will be seen on the global tag page by others visiting the same topic.
Reply to every comment if you can. That makes them come back to read what you and others have written.
Have the Recent Comments, Recent Posts, and Top Posts widgets on your sidebar because people are nosy and want to read what others are saying.
Have the Search bar widget on your blog because people will leave if they can't find what they are looking for.