It took us a full night (2nd half first night/1st half next) to kill yogg on heroic. We spent a good 2ish hours wiping in phase one. Once tanks master it, phase took us maybe an hour, and phase three took us 2 tries.
Phase one, there are two strats. The first is the taxi-style, where a tank brings the mob to the door and everyone DPSs it down. Someone calls to stop DPS, and the tank runs it to the center and 3-4 ranged DPS finish it off. Two tanks + one plate user is more than enough to do this. Make sure the non-tank uses full tank CDs to survive, and its clear hes tanking. The other method of phase one is just to have all the melee + tanks stand in the center of the room. If you have 6 healers, you just heal melee after the explosion. If you get the +damage taken debuff, you mus run out of the center. This strategy is more raid explosion damage, but its easier to kill the adds.
You may also want to spawn two adds at the start of P1, but they nerfed the spawn speeds in the encounter. No one should be dead going from p1-p2, and you want no more than 1 add up at the transition.
Phase two is pretty simple/easiest phase in 4 keeper yogg. Everyone needs to understand their priorities. Everyone needs to turn and hit constrictors. Ranged DPS need to focus on killing crushers. For melee, you can have them stand near raneg to make it safer/prevent deaths, but if a corruptor is ever in range, melee goes over to kill them asap. When there is 6-7 seconds on portal phases, you want people to have SPECIFIC portals, and them READY to zone in.
The brainroom is really what makes or breaks the fight. The faster the door to Yoggs brain opens, the faster all the tentacles outside get stunned. If you get the stun with ike 37+ seconds, it also prevents another crusher spawn, which is HUUUUGEEE. There are a few ways to handle the brain rooms (which there are three of, the Chamber f Aspects room is by far the worst, the armory is decent, but not as good as Shadow Vault, which has 9 tentacles in packs of 3 and can be AoEd.). The easiest is to send the whole raid in a circle going clockwise. The important thing to do is just make sure that you do NOT stop. You non-stop keep running and hit and move, but if youre at the end, make sure tentacles are dead. There should be 9 physical DPS + 1 healer. You can actually do it with 10 physical DPS, but its a bit risky. However, if you have like 2 rets/2 ferals, its more than enough heaing with all 4 keepers up.
The other method of the brain is to have 5 people go clockwise, the other go counter clockwise, then zerg down the center. This is slightly more efficent. The most superior strat, but requires SLIGHTLY more coordination is to assign each person a specific tentacle. This is by far the fastest stun, and the safest amount of damage. It is pretty much a "must-do" if you do 1/0 keeper yogg. Either way, once the illusion is shattered, you have a hunter switch to pack if possible and run right to the brain. If it is the armory or shadowvaut, you want to coordinate a BL. BL and blow CDs. Our first kill took us two brain phrases, but three is very doable with 4 keepers. Hell, four brain rooms is doable, but not preffered.
Phase 3 is pretty easy. The most important thing is to group up FAST, and have all hunters + all melee or even a caster and two on immortals until there is one immortal up. At that point, melee alone should be enough to deal with immortals. If tanks arent bad, and melee dont rip, and you have a few affliction warlocks/spriests, youll kill thje boss. If you take 4 brain phases, you will nmeed to be weary of the enrage. If needed, just have everyone switch to yogg and ahve tanks/healers use cooldowns and burn the boss. If you Bloodlust on the first or second brain, you can bloodlust twice pre-enrage.
In short, let tanks learn p1. Assign decent players to kill mobs in the center. Good transition to p2. Healers/any dispellers need to dispel in 2 as much as possible. People need to know what portals to do/who to DPS. Open the braindoor ASAP. Also, you should assign paladins to enter the brain on opposite sides if youre sending in more than one. YOu can BOP players out of constrictors, and saving BOP for portal-spawn constrictors is ideal. Control the start of P3, bloodlust twice if possible. Also, make sure someone BLs outside of the brainroom when melee pops BL. Its the best use of an outside-BL to be used when the tentacles are not stunned. Also, in p3, have healers stand a bit away from Yogg. This allows for tanks to easily grab the mobs and keep their back safely to yogg, and allow melee to hit yogg.
Feel free for melee to aoe the boss, or have melee tab to hit the bss a few times. you can watch my vid for examples of te fight. You can also search for "yogg portal positions" in google and find a pic for the single-tentacle per person strateegy guide on MMO champion forums.