When fighting the regular groups of mobs, sleep the adds and go after the biggest one first. Mark them in order before you spring Shield Lob. If you don't have sleep, your healer needs to be on top of their game.
When fighting first boss, the adds need to die fast. Tank should hold boss. DD kill adds.
Second boss fight is where the goblin appears half way through with a mob chasing him. Tank and spank until the second mob attacks. Then the first boss should be slept, if possible, and everyone swtich to the second boss. The goblin will randomly do Grenade Toss where one of the party members is standing. Get out of the AOE as fast as possible once he does. Kill the second mob quickly and then switch back to the first. The goblin will troll the whole fight. You just gotta deal.
Third boss fight typical tank and spank, while moving away from AOEs. Occasionally, the boss will trap a character in a bubble that DOTs. The bubble prevents the trapped player from doing anything except attacking the bubble. When the bubble appears, everybody needs to focus on destroying it ASAP so that the trapped character can get back in the fight. Near the end, the dragon Aiatar will show up. Tank and spank and avoid AOEs until he runs away.
Fourth boss is Aiatar again, and this time he must die. Tank should consider the room like a sort of giant clock and start tanking him at anywhere between 12 and 3 o'clock, keeping in mind that you enter the room at 6 o'clock. So tank has to run across room, grab and pull him to 12-3. It is imperative that all players avoid his cone poison AOE. He will randomly spit it at a character. When this happens, you must either Stun it somehow, like Shield Bash, or get the fuck out of the way. If you get hit, you take massive damage and also get a DOT on you which the WHM can get rid of w/Esuna. Eventually, the dragon will start spitting these giant puddles of poison on the floor. They remain there for a certain amount of time, and anybody standing in them will take DOT and also get a Poison DOT, which the WHM must remove w/Esuna. Keep in mind that if you are standing in it when you get the Esuna, you will get poisoned again. Lastly, if the dragon is standing in the poison, he slowly Regens health. At this point, tank has to pull the boss to another position in the room, another point on 'the clock.' Try to keep the boss somewhere close to the poison puddle but not so close that he's standing in it. The idea here is to minimize where he spits the next puddle. By keeping him on one side of the room and tanking him in a circle, you keep the floor as clear as possible for the fight. Although by the end of it, there will be poison everywhere. But in most cases, there's always a sweet spot you can move the dragon to where he doesn't heal. At 10 percent health, the DD should limit break. Repeat until dead.
Hope that helps.