Building a list of RSS feeds takes time. I find that when I stumble across a new site (regardless of how I got there), I poke around to see if the content is interesting. If so, I seek out an RSS feed for it.
Note there are ways to get an RSS feed from some sites without them (RSS-Bridge[0] is what I use), but the experience is much better if the site natively produces one.
In time, you'll find yourself with hundreds of feeds on a variety of topics.