How do you become a music journalist?

Take a good notes.

Start a blog, make sure to tag your stories. If you get a lot of people following you important people will start to take notice. Also write articles and send them to magazines or newspapers. They are often looking for freelancers. If they have samples of your writing they may consider you for a future project even if they don't take your first article.

You write and get good and get your words noticed. I think I'd be good at that too, but I'd rather make music than write about it. Though I might write some reviews at some point just to see what it feels like... I did a few on prograchives.com actually, but those aren't great. But yeah, that sounds like a perfect job for you.