[gnosis]

Comment timing and choice of article to comment on are huge factors for how highly rated comments are.

If you manage to comment relatively early on an article that winds up being popular, your comment is much more likely to itself be upvoted (or downvoted) a lot.

The later you comment, and the less popular the articles you comment on, the less chance your comment will be voted on at all.

I've often commented on articles which were "old" (by HN time) and on articles which I personally found interesting but which which hadn't received many upvotes, and those comments were very rarely up or downvoted (probably because most people never even saw them).

Comment placement is another important factor. "Top-level" comments (ie. comments without any parent comments) are more likely to be voted on than comments buried deep within a thread. Though replies to high rated top-level comments are often more likely to get voted on than top-level comments which appear later on an article with a lot of discussion going on.