As Detrimental said I have analyzed a lot of the data from the combat log. I have mostly been looking at what I could do better, but I did see a few other things:
The Attumen battle
At the beginning everyone attacks midnight until Attumen shows up. The main tank takes Attumen and pulls him away from the group so he can't cleave anyone. At this point all damage should be focused on Midnight. No one except the main tank should bother with Attumen.
There was some difficulty transferring the boss from Annux to Arvernien. Attumen is immune to taunts so everyone has to stop DPS except the main tank. It's hard when he's beating on you, but turn off auto-attack and stand by the main tank.
Once the battle is engaged and Attumen is clearly on the main tank everyone else needs to be within 8 yards and at the horses rump. If you are in the front half you will be hit with a shadow cleave which does ~4000 to cloth. If you are more than 8 yards away he'll charge you which does ~3000 and a knock down affect. We didn't have a problem with the charge, but a few people were inside the cleave range.
Other battles:
In general we need to have a few seconds of patience and let the main tank/off tank cement threat on the mobs before DPS starts. It really means wait a few seconds before casting. Hopefully, you will find a paladin or another warrior willing to tank (I wish I could be there). Let him start building threat for at least 3 full seconds, then start your long (3 second) cast spell. Threat generally was pulled by someone who waited one second then cast a fast spell that critically hit the target. The caster was then instantly put on the top of the threat list. That's when the beatings really started.
Omen
Make sure you have the latest version of Omen, when soloing look at your TPS (threat per second) and make a note of it. When you then join with someone who will tank for you compare your TPS with theirs. It's okay to be very close, but don't exceeed it.
Deadly Boss Mods
I recommend someone have this mod. It keeps track of boss actions like spell timers and other scripted attacks (like Blackheart the inciter's mind control). The user of this mod can also broadcast to the raid the remaining time until such actions.
Finally
Have lots of fun and I hope you are able to defeat both Attumen and Moroes!