Ilam,

I struggle with the same questions. Since I'm a beginning writer my solution was to not try to answer it for a while.

Instead I decided to follow the rule that for the first 100 articles I write, I will just write about what I am excited about.

At the end of 100 articles I figured I could get a good idea of my strengths, my preferences, and my favorite themes just by looking at my writing history.

Another thought - if this is your joy, and you don't care about the money, maybe just let joy be your compass. Write about the things you love, with such force and clarity that your audience can see why you love it.

J