Great guide Frankie! I think I might be guilty of several things that you mention, though there is something I might not 100% agree on. Regarding advertising, and getting bigger as a channel, considering I'm still rather small on YouTube (as of present day), I feel that I still don't have a solid following, as most of my audience tends to be from just random viewers (passerby's as some would call it.. lol). I also find it similar to a catch-22 where one needs to have a following to get more of a following.
I still kinda think that small channels need to piggy-back a bit (now of course, not over doing it or making it blatant) until they get to a point where they have a solid following because I know of a lot of people that make good content, yet they're never known since they haven't been exposed to the masses outside of their cave.
As dweebmodeon once said "Spamming is a small channel's bff" and I can understand where he is coming from. Though of course, overdoing it is never good as that would cause unintended consequences. In short, I think it is ok to advertise it as long as one isn't overdoing it or making it to the point where it is very desperate and annoying. For example, a gamer that does an LP of Castlevania tells others Castlevania fans to check out his Castlevania LP, or even tell other retro-gamers that do it.