Well, it's a good start but I have a few things to add. I'll start with the trash mobs.
Envoy of Elements: As has been mentioned, these guys will periodically cast a freeze spell that will freeze everyone in the party for about 10 seconds. It's important to recognize these guys and kill them ASAP. Prior to the tank pulling you should have players with CC/stun spells targeting the envoy of elements. The DPS should lock down/stun and promptly kill them so that you don't need to worry about the party being frozen and someone getting hacked down and killed before it wears off.
Earth Giant Guards: You will find these guys further in the instance. I believe you first start seeing them on the way to Pangkor. The Earth Giant Soldiers will use a spell called quake, if interrupted they drop easy and no harm done. These guys on the other hand will start casting a spell as soon as they are aggroed. When they get a ways through the cast everyone in their LoS will be locked down and start taking around 2-2.5k per tick for around 4-5 ticks. You cannot stun them so don't bother trying. There are two methods for dealing with these guys, they are as follows.
Method 1: Have everyone "bum-rush" them and take them down ASAP, before they can start dealing damage with their AoE. This works wonders but only if you have adequate DPS. If not then method 2 is the way to go.
Method 2: Move everyone behind a thick wall that is out of the Earth Giant's LoS. Next have a single person with ranged attacks aggro it and then run back out of it's LoS. Then you just wait until he finishes casting his spell. If done properly the giant will cast its spell and nobody will take damage. It will finish casting it's spell and then run toward the group, at which point you kill it ASAP so as to avoid another spell-cast.
For much of the instance with adequate DPS this can be done using method 1. However, a few places have two of these guys and you really have no choice but to employ method 2.
Fire Giant Captains: These guys are hands down the hardest trash mob you'll find pre-hoto, provided you don't fight them properly. They are in the room that Thynos is inside and you need to kill all of them before engaging Thynos. What you need to watch for is when they start glowing. When they do this they will promptly summon a miniature fire-elemental looking thing called a Fierce Soldier. These little guys will run at the party and explode on impact (think it's the furthest target away but not certain on that), dealing around 7-9k to everyone that is near the explosion. The best way to avoid this is to assign someone to "stun-duty". This person will focus on waiting for the Fierce Soldiers to appear and then promptly stun them. If stunned the Fierce Soldier will not explode and it will just sit there smacking whoever it has aggro on. The Captain will summon one near the start of the fight and then continue to summon another every 10-15 seconds. So it's important to kill the Captain ASAP.