I always thought the rule of self-promoting in the Youtube comment section is to not self-promote in the Youtube comment section Good guide though. I'd also add to try and make it as non-obvious as possible when self-promoting yourself in others comment sections. Such as "Great video, <Upoloader Name>. I've been a fan of you for awhile and a lot of my videos are inspired by your content ^.^". Though definitely don't say something like that unless it's true. You don't want to seem like a fraud.