I wish I'd been told that it all doesn't have to make sense together. In Marvel, for example, there are SO many different versions of characters and even different versions of stories. I'm the kind of person who is never going to be able to read every single comic, so I get my knowledge in bits and pieces--animated series, movies, graphic novels at the library, old issues at book sales/stores, etc. I wish I'd been given some sort of guide to keep the different ages/universes straight. Instead, I tried to make sense of it all together in my head. So I have a very unique but strange headcanon that tries to piece it all together in ways it was never meant to go. It makes for some great ships and OT3s, mind you, so I'm not really complaining. But it would have been nice to have been given permission to not try so hard to make it make sense as a whole.

Also, it would have been nice to know what authors to ignore and which to pay attention to. Again, I'll take anything. But because of that, I've waded through some really terrible representations of certain characters. When you treat everything as equal, you never know what sort of weight to give to a story, and then you're entirely unprepared when you happen to be reading one of the good ones without knowing it and the Joker suddenly shoots Batgirl. I had to learn the hard way that there are some authors to ignore and some to gravitate to.