Baby Beacon is the new all-star
Protector of the Innocent has completely changed the way I play my holy paladin, and it's definitely for the better. The basic concept is that any time I use any heal except Light of Dawn, I heal myself for a free 5,000 health. Think of it as a "Baby Beacon" that is cast on yourself at all times. The heal scales with spellpower and it can crit, and it doesn't matter how powerful your original heal was. Every single Holy Shock or Word of Glory is healing me for a significant amount, even if I'm healing myself. Because of this, I'm able to survive just about anything that's being thrown at me without having to worry about my own health.
Back in the day, on heroic Marrowgar, my guild kept into running into the same problem every week. One healer would be spiked, I would have to move out of a Coldflame, and we'd start losing players. I came up with a new strategy to deal with that issue -- I put Beacon of Light on myself. After that point, I would simply stand still and drop my biggest healing bombs on whoever I liked, without ever needing to move. I'd be getting cleaved by Marrowgar and standing in Coldflame without even faltering for a second. As long as I continued to cast, I was invulnerable.
Healing three people at once
With Beacon of Light on yourself, Protector of the Innocent more than compensates us for the 50 percent nerf that Beacon saw in patch 4.0.1 when trying to heal yourself. With Beacon of Light on another target, you're literally keeping three people alive every time you cast a heal. With Light of Dawn healing multiple targets (including yourself), you can seriously keep your party up through some pretty punishing damage. I was worried about our AoE healing without Holy Radiance, and while we're not up to holy priest or resto druid levels yet, we're able to keep multiple targets alive with ease.
Use your instant spells
Put a sticky note on your monitor. Have Power Auras yell at you when they're off cooldown. Bind every key to Holy Shock. Whatever it takes to get you in the habit of using Holy Shock and Word of Glory as often as possible will be worth it. I initially had a hard time getting used to using Holy Shock as a primary heal and even trying to get Word of Glory into my normal triage methods. I ended up swapping Holy Shock and Holy Light's keybind on my action bar so that every time I would've gone for a Holy Light, it'll try a Holy Shock instead. While it might be crude, we need to get in the habit of using Holy Shock and Word of Glory as often as possible.
Our mana pools are going to be balanced around using HS and WoG often. HS is one of our cheapest and yet most powerful heals, while WoG doesn't even cost any mana at all. Between the two of them, we'll be doing a significant amount of healing without denting our mana pool. Think of the HS/WoG combo as the old Flash of Light -- it doesn't even dent your mana. Our other heals are used when HS and WoG can't handle the damage, and we draw on our mana reserves to keep the raid and tanks alive.
Our new fire hose
I'm not going to pull any punches here: Our single-target throughput is never going to be the same. Holy Light was too quick and too powerful for what it accomplished, and I am certain that many holy paladins will remember with great nostalgia the time we spent in ICC as tank-healing gods. Unfortunately, we live in a post-4.0.1 world now, and we've got to adapt to keep everyone alive. Divine Light is the right tool for the job. Well, it will be the right tool once tanks have massive life pools and we have free time to cast slower spells. In today's pre-Cataclysm period, Flash of Light is usually the better choice. That's going to change shortly, though.
The basic idea is that while Divine Light takes longer to cast than Holy Light does, it also heals quite a bit more health per second. Unfortunately, its mana cost is also significantly higher. If you can, you want to heal someone with Holy Shock first, as it's cheap, quick and powerful -- the perfect heal. Holy Light is the heal of choice for picking up life bars efficiently, albeit slowly. Flash of Light can actually put out quite a bit more healing per second than Divine Light, but its mana cost is pretty prohibitive. FoL is better reserved for the heroic Marrowgar situation in which mana isn't an issue and you only care about keeping everyone alive. When you've got a tank getting slammed, look no further than Divine Light to keep him afloat.
Learning to manage our mana is going to be the most important skill we learn going into Cataclysm. Holy Light is easy enough to spam all night long, but we need to anticipate high periods of tank damage and swap to Divine Light. If the entire raid is going to get lit up, then Flash of Light becomes our only option. Basically, we have to figure out how much HPS we're required to put out. Light of Dawn and Holy Radiance are the wild cards in this model, although I have been using Light of Dawn on cooldown just because it looks so awesome to cast. I haven't had any mana problems when using the Glyph of Divine Plea and making sure to use Divine Plea during any sort of down time, such as the Tear Gas phases of Professor Putricide.
The Light and How to Swing It (Holy Edition) helps holy paladins become the powerful healers we're destined to be. Learn the ropes in Holy 101. We can help you keep a tank alive, heal a raid when necessary and beat the global cooldown. Tanking is a job, DPS is a craft -- but healing is truly an art.