Blog Commenting - This means looking for blogs (if it's a high traffic blog, much better) which have similar theme or niche to yours. You may want to subscribe to its feeds or add it to the blogs you follow via Google Connect so that when new posts are up, you can get to make the first few comments. (Some bloggers may also follow you back, which is good for building more links to your blog.) Remember not to leave spammy comments but valuable information so that first it won't be deleted and second it may interest other readers of the blog to click through to your blog.
Socialize - Don't underestimate the power of social media. The world has seen powerful changes through the advent of social media.
Back to promoting your blog, you can post links to your blog posts in your social networks like Facebook and Twitter. It is one way of letting your friends know what you're up to and if they like the info or find it interesting, they would click through to your blog.
Network with other bloggers by joining communities like the BlogFrog, and Entrecard. They are free to join. The main purpose with these blog networks is to get the word out about your blog to other bloggers, making some loyal blog readers and friends in the process. I've made some regular blog readers and friends because of this.
One feature I like about the BlogFrog is that when I visit a blog with the BlogFrog widget in it, my profile gets displayed which is free promotion for me. I can also follow other bloggers in the community, get followers back and participate in discussions. For Entrecard, you get to search a lot of blogs categorized to niches and when you visit them you can drop an entrecard so that the blog owner would know you visited them. Many if not all will visit you back. You can also advertise on other blogs by displaying your widget on their site in exchange for earned credits from visiting Entrecard members' blogs. If you haven't joined Entrecard, try it.
Advertise - Blog commenting and PR works in blog communities takes a lot of time but they're free. If you want to free yourself from these time-consuming activities, you can always advertise if you can spare some budget for it. You can look for high-traffic sites or blogs and see if they offer paid ad spots. Or you can advertise through advertising services like Adbrite, Bidvertizer, and Adgitize. Adgitize is one advertising company that many bloggers like. It costs only $14 per month and you get to have your widget displayed across the Adgitize blog network. Many say that they get an average of 70 visitors a day from Adgitize. Many argue though that it is not targeted traffic, but still you get to promote your blog to a lot of people. If you're writing very good content, surely they would like to come visit again. Another good thing about Adgitize is you can get a part, full or even more of what you paid for when you display Adgitize ads on your blog. Isn't that really nice?
I will make another post about Entrecard and Adgitize next time where we can help each other increase traffic for our blogs. Hope this blog post has been helpful. If you have more suggestions or comments, feel free to add your thoughts. I like learning more about this topic also.