Thanks for the reply!
My general idea was to blog about a lot of different things, but i figured out that I will have to scale it down a bit, so the main things will be: giving tips about upcoming music events, album releases and new songs.
Since I study music it would be fun to make the blog about how to succeed in the music industry. In that case I could include mini interviews with people in my surrounding who are more experienced and sort of help other people like me in how to make it.
This blog will be a part of a school project and the main issue is how to make it interesting, like you said, I have to come up with some kind of niche, and I guess that's the hardest part.