Thank you for this post. As a newcomer, it's good to learn this unwritten rules, but I have objections in two cases.
Also, never, ever, ever, upvote your comment and skip upvoting the post. That is simply rude.
What do you think about the following scenario? The commenter comes across a very objectionable content and the comment section is full with objectionable comments as well. The only way to stand out in the crowd and make a counterargument is to upvote the comment, but the commenter can't upvote the post, because the commenter completely disagrees with it.
It is when one leaves a comment and then puts a link to an article he or she wrote. Do not do this.
How about writing a lengthy comment and then providing the links for reference? And what if the commenter has hundreds of posts in their blog and the referenced posts are somewhere towards the bottom of those hundreds of posts. In that case, it would be a pain to look for those posts, no?