Submitting your blog to RSS & blog directories is considerably easier than submitting fully-functional sites to website directories. This is because there are free, automatic systems in place that allow you to submit an updated version of your blog to directories without doing any form-filling.
This automatic system for submitting your blog to RSS & blog directories is known as pinging. You ping your blog at sites like kping.com and pingoat.com. When you ping your blog, the system will automatically send the latest update from your blog to all of the largest blog directorires - usually on the order of about 40 or so. This means that submitting your blog to RSS & blog directories can actually be as simple as filling in your URL and title - and then hitting submit. The only thing you will want to be careful about is the title you use. You will want to make sure that you use your most targeted keyword in the title you submit, as that will be attached to all of the backlinks you receive from these directories.
Additionally, submitting your blog to RSS & blog directories will get your blog placed on the front page of a number of blog directories. This may generate some quick traffic for you from people who are looking at the latest blogs to be updated.
Once you are finished submitting your blog to RSS & blog directories via ping, you will then want to search out directories that you cannot ping and submit to them individually. Vilesilencer.com provides a fairly complete list of RSS and blog directories. You will want to first submit to directories that offer certain perks (i.e., first page listings) or have higher PR - as this will confer higher more PR to your blog. Since you cannot submit to most RSS directories via ping, they will probably make up the bulk of your submissions.