We often hear some say that Paladin healing is boring on the base of spam Flash of Light on the tank Paladin use and cast the occasional Holy Light to recover from burst damage. On the view of Paladin healing, while not completely baseless, is more of a stereotype than a reality, and we'd like to give you, some comments on Paladin healing.
   While Paladins only have two viable healing spells, there are a wide variety of schools of thought pertaining to Paladin healing and what stats and spells to focus on.
Flash of Light is seven ranks total, though only the max rank is commonly used. When we type Flash of Light it refers to the max rank.)
HL - Holy Light (11 ranks total, and ranks 4-11 are all used depending on a Paladin's style.)
HS - Holy Shock (Five ranks total, though only the max rank is used. Due to its cool-down, high mana cost, and short range, HS is only used in rare circumstances where the tank must be healed immediately or he will die.)
Healing per Second is HPS in short.
About Paladin healing, the important thing for you to know is how to cast Flash of Light. We cast it a lot. The main reason for this is the Flash of Light is very efficient and provides a great deal of healing per mana. By chain casting Flight of Light on a tank who is taking consistent damage, Paladins can keep him up for a long time and almost indefinably if a Shadow Priest or Restoration Shaman is in our group. The main problem with that statement, however, is that in most fights tanks take anything but consistent damage. That's where Holy Light comes in. While not as efficient as Flash of Light, Holy Light provides much more HPS and lets you get your tank back up to full faster.
That was the simple explanation of Paladin healing. The complicated part requires discussion of an interesting Paladin talent called Light's Grace. As you can see in the tooltip, Light's Grace shortens the cast time of Holy Light from 2.5 seconds to two seconds, which, as any healer can tell you, can be the difference between downing a boss and your tank splattered all over the floor. All Paladins, regardless of their methods, should keep Light's Grace up at all times. This allows you to drop a big heal like Holy Light 11 .5 seconds faster. Most Flash of Light spamming Paladins use either Holy Light 4 or Holy Light 5 ever 10 seconds or so to keep Light's Grace up and otherwise use Flash of Light.
And also down ranking Holy Light is an important part of Paladin healing. If Flash of Light can't keep up with incoming damage, we tend to throw a few HL9 into the mix, which not only brings the tank's health back up, but keeps Light's Grace up as well.
Overall, Paladin healing is not just Flash of Light spam, but rather is a delicate balance between efficiency and keeping your tank alive. Therefore, Paladin healers must be aware of their surroundings and know the ideal spell to cast in order to maximize efficiency while minimizing over-heal and keeping the raid topped off.
At length, for any new or learning Holy Paladins out there, always value keeping the tank up over efficiency (something we had to learn as well). Your tank doesn't care that you are at 50% mana nine minutes into a fight if he's staring at the spirit healer.