Originally Posted by
speehs
Healing is more about intuition than it is a set method or rotation. You have to play around with your spells and get a feel for how much they'll heal a given target, how they interact with your other spells, how fast the cast will finish, etc. That way when the tank takes a damage spike or someone steps in something they weren't supposed to, you don't have to stop and think "well should I use Flash Heal or Greater Heal?" After some practice, you'll just know which heal to use in what situation and do it automatically. Sometimes those split second decisions can make the difference in a wipe and a kill.
Although it may seem hectic at first, LFR would probably be your best bet on learning how to properly raid heal without the stress of a real raid. The other healers will be able to keep the raid up if you make mistakes, so it's not all hinging on your performance. Try to heal people who are taking a lot of damage to get a feel for your heals. Go for the easiest raids first, then work your way up, even if your gear is good.
Also, try mouseover macros for all of your heals. Being able to cast a heal without clicking a raid/party frame saves a LOT of time and makes the gameplay a little more fluid.
But most importantly, don't get discouraged. Like anything else, learning to heal takes a lot of trial and error. But once you master it, there's nothing more rewarding in the game (imo). That's why I've been doing it since BC.