I wanted to make a nice list of thing that I would consider to be common courtesy for in-game behaviour, but I'm not really good at that type of thing, and some people would be displeased with the demanding nature of such a list. Therefore, I shall simple put forward my thoughts in the form of my opinion.

From my perspective, this is a game. It is something that is for fun. When I'm doing a dungeon or some such, I don't really care if someone else doesn't really know what they are doing because I can find the dungeon fun whether we win or lose. At least that is what I would like to say. But really, when things start to not go well, I get worried that someone else is going to get mad, especially if there is a chance that I'm the one not doing well. I dislike it when other people get mad at each other while playing the game.

It is my opinion that if a person does not enjoy simply playing content for the sake of playing content, that person should search out an FC or group of people who wish to play in the same manner as themselves. If people are going to play in the DF or PF with people that they don't know, it would be nice if everyone one would be civil and pleasant. Of course, as a recommendation, it is best for those who don't want to be overly serious to also find an FC to play with.

As for the OP points, I like being over-geared because it makes it so I can get through content without feeling like I'm going to pass out.
I prefer not using guides and videos, because, well that's kind of lame/boring.

Ultimately, I simply wish people were nicer/more sympathetic to each other. But don't worry everyone, I'm not insane. I know that won't happen.