Hyperlinks, RSS, and a bit of routine maintenance. When you stumble upon an interesting article, subscribe to the author's feed. If you lose interest, unsubscribe. You will eventually end up with the information source you want.
This is the crux of the issue. Either someone (perhaps the owner) tells you, or you ask someone who knows. The former is distinct from discoverability, so that's out. When you ask though, you want to ask someone who knows lots of things, which is likely to be corporate (major search engines).
When you google a question that interests you and find an answer in a blog, you see if there are more interesting stuff there.