I'll often just read the comments, or read a portion of them and possibly even comment (if it's not entirely related to the submission, as discussion drifts), prior to reading the article. If what I'm commenting about is related to the article and I haven't read it (such as noting related info), I generally do a quick scan and search of the article to make sure I'm not repeating what it said.
I don't think there's anything wrong with reading comments first, and in some select cases commenting yourself. Comments are why I'm here. That said, it's worth keeping in mind whether you've read the article though and how that affects your interpretation of what you're reading, and what you want to say. Be signal, not noise (I think that's a perfect motto for HN and summarizes the rules fairly well).
I don't think there's anything wrong with reading comments first, and in some select cases commenting yourself. Comments are why I'm here. That said, it's worth keeping in mind whether you've read the article though and how that affects your interpretation of what you're reading, and what you want to say. Be signal, not noise (I think that's a perfect motto for HN and summarizes the rules fairly well).