Having recently cleared t11, i can chip in for some tips i found useful.
I'm not skinning as much as i'd like, mostly because it just drains the mp.
We are also doing ph1 with one tank in front (meaning tank needs to know his cds).
Medica2 on lasermissile (or after the the spreadmissile).
I tend to 1st Shroud at 80-83% on boss, so that it's up again once adds pop.
At 1st phase, cleric + aero + aero2 + fluid on Nervegasses helps out a bit ( 8k dmg done, we beat enrage by 4 sec).

Add phase is where the fun starts. We got 2 melee + bard + pld at ball, while the rest are doing their job. First Repelling I throw DS medica2, then next one Cure3. On the 3rd Repelling I throw in medica2 + medica (if people are not topped/near topped). 4th is Cure3 time and then 5th I think DS is up again for medica2. For tank healing, I tend to only use cure1 + regen when needed.
I tend to enter Addphase at around 4,1k-4,5k mp and Shroud on top of that when cd is down.
Generally Addphase you should leave the other healer (I would guess sch) the majority of tank healing, while you refresh your mp between aoe heals.

I tend to enter last phase at around 3k mp (Shroud is up after adds are dead). At this point the tanks are dancing together and shouldn't take any massive hits when Resonance is split.
Again I tend to not skin unless it's really really mandatory (Headcombo).
Also note, PLD can/should skin themselves on Nerves.