Stagger

I try to build up the stagger bar and sometimes it's real easy as the yellow part goes very slowly down, but other times it goes down so fast that it'll reach zero even between two consecutive attacks so there's no possible way of keeping it up. It all seems extremely random to me, but it probably isn't.

help :(

Try chaining your attacks together at once. :)

Ravaging attacks seem to be about the only thing that really push it up. Spells like Aeroga and stuff. Commando attacks can't really do it unless you all gang up. It's a little annoying if you're in a party who doesn't have at least two ravagers.

Ravager's build up the bar, HOWEVER Commando attacks will need to be used in order to slow down the rate it decreases. Once a commando hits it once, change to ravager and chain it.

Slowing down the rate is exactly what I'm looking for, and even with a party full of ravagers it didn't help, so thanks dignified pauper I will try adding some commando in there.

As Pauper said, Ravager attacks build it up quicker, and Commando attacks slow the rate the bar decreases. I've found it works well to start with one Commando to slow down the decrease rate a bit, and then go to all-Ravager attack mode to quickly fill the rest up.

My default is set to two ravagers and a commando.

What Raist said.

Yeah, I tend to alternate between a set like DP's, a set with a Commando, Ravager and Medic, and a start-up set that does buffs and debuffs enemies and casts slow and stuff while one is a medic, when I have 3 folks.

Suddenly things became that much easier

I start with two ravagers and a commando, then switch to two com and a rav. I don't bother much with buffs and debuffs unless boss fight.