In followup to my post yesterday comparing Holy Paladins to Resto Druids, I wanted to continue the analysis. I touched on the basic differences between the healing styles and gave examples of how either would heal in 5-man content but I think that bears more examination. 5-man content is probably where you'll begin your healing career, so it's only right that you know up front what it will most likely look like for you. First, as a general rule, don't start healing until you are actually ready to heal. You can easily DPS and pick up healing items such as rings, necklace, and trinkets from various instances, while earning the badges you need for a full ilevel 232 suit. And that is really what I'd recommend. There just isn't any better way of getting into healing than assembling a T9 suit, which of course means running enough dungeons until you can earn 210 badges for the five pieces of T9, another 25 for the ilevel 245 Libram (or Idol as a Druid), and probably another 70 as for the Ring of the Invoker and Heartmender Circle off the Triumph vendor. You can probably spend another 19 emblems on the Frozen Tear of Elune necklace off the conquest vendor (unless you loot the healing necklace from Forge of Souls) just to round it all out, for a grand total of 324 badges. That seems like a lot but it really isn't. If you run just 5 dungeons a day you can probably get everything you need in 10-11 days and pick up the remaining pieces like a belt, boots, bracers, and trinkets from TOC, FoS, PoS, and HoR.
Once you have all that stepping into 5-man heroic healing will be very much easier than trying to break into healing with greens and blues. Which isn't to say that it can't be done, but running heroics today is really a different proposition than it was six months ago. Today your tanks are typically better geared and more prone to fast runs through chain pulling. It's much more likely you will encounter problems under those circumstances in typical starter gear than in an epic suit you can easily assemble.
As a Holy Paladin you generally want to keep your beacon either on the tank, or on yourself if you're in an instance that features a lot of AOE damage like HoR, TOC, FoS, or PoS. With the suit I'm recommending you'll find yourself around a 4700-4900 gear score and will probably be able to hit 4-5k with Flash of Lights, and FoL Crits in the neighborhood of 6-8k. As such you'll probably just want to use FoL spam heals throughout the instance, as I doubt you'll need to use Holy Light at all, or at least very infrequently. FoL and Holy Shock will be your staples, as will Sacred Shield. FoL healing is mana efficient, but you want to judge whenever you can to give you those haste buffs and to regen even more mana through judgement crits. It sounds funny, but judging can be an integral part of your healing rotation and I routinely scan health bars, then look at the timer of my judgment spell. My eyes are constantly moving so that I can anticipate when I will next judge. Outside of that it's a simple matter to keep Sacrificial Shield up on the tank and spam FoL on the tank or on party members. I'll often keep Holy Shock in ready to use as a mini emergency button for a party member that is taking some damage, but in an AOE damage fight I'm spamming FoL on each member in quick succession. I'll target the first member, get FoL going and immediately target the next before FoL lands on the first member so I can immediately start healing the second. As Beacon will most likely be on yourself of the tank you only need to do that with four party members and shouldn't have any trouble keeping the party up under all but the most extreme damage.
Whereas you are somewhat more reactive and have to pay a bit more attention to you part as a Holy Paladin and not care in the least about your over-healing, it's a different case as a Resto Druid. As Resto it's all about HOTs, though since WotLK was launched Resto Druids now have their first quick direct heal spell in the form of Nourish. As I looked into the specific spec I wanted to go with, it looked like Nourish was more about raid healing, so I didn't take the talents that reduced it's cost and didn't glyph for improved Nourish healing. You might use an occasional Nourish in a group, but your primary heals are going to be Rejuv and Wildgrowth. Meaning you will have to exercise a little more discipline than you probably would as a Holy Paladin. You have mana regen mechanics based on spirit as a Resto Druid and you will probably notice you aren't out-right as mana efficient as a Holy Paladin. So you will need to let your HOTs do their work and not spam rejuv on the tank every 4 seconds. And that essentially is the main difference between healing styles.
As Resto I'll keep Rejuv up on the tank at all times, along with wildgrowth for constant group healing. I'll add a Lifebloom, and a regrowth tot he tank as the situation warrants and can throw a rejuv out on any individual in the party that needs a little extra healing than wildgrowth. This type of healing is ideal for chain pulling tanks who are constantly on the move. Especially those who don't even stop to loot because your heals are still working even if you aren't casting. You simply don't have to be as attentive --I almost hesitate to say that-- to the party as you do for a direct healing class. Which isn't to say that you don't need to be attentive, but with your heals constantly ticking on the tank and the party you don't have to have worry about taking your eyes off healing bars for a second or two.
I enjoy both styles of healing very much, though I'm leaning toward the Holy Paladin as my preferred Raid healer and my Resto Druid as my preferred PVP healer. If you are new to healing either would be a terrific choice to start out as.