I'd say the worst advice I have ever received is the sub for sub method, and upload only "quality" content. Why yes it's good to promote better videos instead of half-assed content, there's always this thing in peoples head that "quality" content is going to be what makes you big, and it's not. It's all about getting your points across, and making sure you are entertaining people no matter how bad the quality is. I've watched high quality, unique videos that are actually worse in some cases, than a generic person talking about his feelings on a specific topic.