First of all, stop looking at effective healing. I play a Resto Sham in raids and I can tell you, if enough Shamans and Paladins (and perhaps Holy Priests) are raiding together with Druids, we will spam heal faster than your hots can tick, causing us to 'steal' your healing done.
A good healer has following attributes:
* You know your class, what gear is best for you, what spell to use when and you know the encounter good enough to be able to hot pre-emptively should it be needed.
* You don't let your target die. If it's raid healing you're doing and they're standing in a fire, then it's their own damn fault.
* If you see another healer struggling and you can spare the time & mana to throw a hot once in a while, do it.
* You tell that nab MT that healing meters are just as good to determine good healers as Damage Taken meters are to determine a good tank.