I was only top ~110 so everything I say is super amplified for top 50.

In a top 300 US guild you just need to follow a Fatboss or Method guide and execute it right and you're done. In a top 100 US guild you need to be doing tons of your own research. My guild had a ton of theorycrafters, some who frequented /r/competitivewow.

I was staying relevant with top DK blogs and constantly simming to see what's best for me. I would talk with the DK contacts I made, exchanging tips and ideas, and experiment a ton. and aim for 95+ percentiles every Heroic fight. Even then I was a mid-tier DPS in the guild, not worth my attendance/attitude problems.

But strats are the even bigger thing. In my guild we outpaced the rate that Fatboss videos were put out, so we had to rely on Method videos that involved low ilvls and no ring. We had to use that, combine it with high end guild input, and do our own strats together, in order to down a boss fast enough. And you couldn't fuck it up.

Another very important thing to keep in mind is that in the 200-500 range you still have a lot of real chill guilds. Top 100 US is full of assholes. I don't mean that in a bad way, just that it's their personality. They admit it. Almost every guild I've seen (including the one I was in) admitted that they are assholes even outside of raid. After multiple top 100 guilds I gave up since I ended up getting hated in every guild I joined since I was a terrible fit attitude-wise. I literally don't have a single friend from those guilds still added.

Why is this important? Raiding is not just about the skill but also about the social experience. I could compete just fine in those guilds, I just ended up getting on the bad side of half the raiders (by my fault), so every time it was a matter of time before something happens and I end up out of the guild. Top 100 guilds are a completely different atmosphere from top 300. Just be ready for it. When in doubt, don't talk. That's the trick.