Bloggers are having a major impact on the music business today. Collectively, mp3 blogs.
Find a niche. There are thousands of music blogs out there. Look around and see what sort of music blogs don't exist yet. Blog the music that you enjoy or you'll run out of energy fast.
Set up a blogging account. Blogger and Wordpress are the most popular for mp3 blogs.
Log into your blog account and post away.
Post songs via a hosting service. Yousendit makes it easy because it has two weeks expiration. It's important to delete tracks after 7 - 14 days to avoid copyright infringement. You can also host songs at mac.com.
Make a link list of your favourite mp3 blogs and write to them asking for a link trade, it's the best way to bring in traffic.
Write a disclaimer. This is very important. Most ever mp3 blog has a disclaimer on the main page stating: these songs are up for listening purposes only for a short time. If you're an artist or label who wants the song taken down, please write the site owner.
Most music sites won't let you upload songs that you don't own personally i.e. any song you haven't written yourself. So you will need to upload the song to your own server.
Keep surfing the web looking for new bands to post. Eventually you will have bands contacting you who wants to be posted.
Research the song. The point of an mp3 blog is to give some background on the songs you're posting. You could also add your own review and your history with the song or band.
Don't post songs permanently, to avoid copyright infringement.