A very simple yet effective way to promote your blog is through the use of online forums. The first thing to do is to find a couple of forums related to the topic of your blog and register up. Big-Boards.com is an excellent resource to find large forums. Currently they track almost 2000 of the largest online boards on the Internet.
Once you pick a couple of forums and register up you will need to customize your profile. Most of the boards allow the user to create a signature, make sure you use it to place a link to your blog with a small description of what users will find there.
Now you are set, just engage in the discussions and contribute with useful information, so that people will want to check out your signature link.