Great post, @condra!
It seems as though engagement is a lot like it is in any other form of blogging. There isn't much point to commenting something vague and short. It's better to take the time to read the entire post, think about it, and respond with a value-driven comment.
Pick something in the post that really stands out for you. Why? Respond to it.
What is something you agree or disagree with?
What can you relate to? What can you add to the conversation?
Creating a community within your audience will lead to better engagement, visibility, and - most likely - upvotes.
Absolutely. And that's why I often comment on Photography/Music posts, because I'm never stuck for anything to say on something in my own niche. Thanks for your comment. Upvoted, of course!