If you want to be famous or reach a wide audience, you will have to choose something slightly broader and work hard to make the best content for that topic. A subtopic relating to fitness, finance, or relationship advice is likely to reach the most people. Consider specific but broadly applicable topics such as managing money in college, or a marriage counseling blog.
Have in-depth knowledge in your niche? Package it up into an ebook and sell it on your blog. I'd generally advise against selling it (at least exclusively) on Amazon or Kobo, as you'll probably be able to charge much less. If you've already built up a solid audience, you can probably change anywhere from $5 for a very short one, all the way up to $39+.
If you’re passionate about something, it will show in your content. Readers will be able to see your genuineness and will be attracted to that. This is probably the most important thing you will learn about blogging. You can try everything in the world and use every tool known to man to be successful, but if you’re not genuine, people will see right through it.
I want you to have realistic expectations, though. Those results are not the norm. My first month of monetizing my blog I made several thousands of dollars. But that occurred after I had been blogging for eighteen months. But do the math – I’m estimating my business will earn six-figures in ** the second year**. And I’ve never monetized a blog before!