Post by lockbox
Coincidentally I also respecced holy from retribution recently.
First thing to do (since you say you've already respecced) is to hit up the reputation vendors. If you've been doing dungeons for a while, you're bound to be revered/exalted with some Cataclysm factions. There's lot of healer gear waiting for you right there. Ramkahen
(Uldum) The Earthen Ring
(Vashj'ir, Silver Tide Hollow) Therazane
(Deepholm) Wildhammer Clan
(Twilight Highlands, Alliance)
Also check out Baradin's Wardens
/ Hellscream's Reach
for trinkets when exalted.
These items are all plate. You can wear cloth, mail and leather, but I would not recommend it - the 5% intellect boost for wearing full plate is too good.
Note that I've listed all items applicable to Holy paladins, not necessarily those that are best. For the other slots, check the auction house for cheap items that people created when levelling blacksmithing and such. Get PvP gear only
if it's a massive
upgrade over what you would otherwise be using - resilience is completely useless in PvE (dungeons and raids) and takes up stat allocation that could be spent in another helpful stat. If you do use PvP gear, replace it as soon as you can.
Now see Blademeld's great Paladin FAQ
for info on what spells/gems/enchants to use and when.
Queue for normal dungeons (then later, when your equipment is 333+ from normal dungeons, heroics) and heal away. There's only so much you can learn from reading. The minimum item level for heroic dungeons is 329... but this depends on the group knowing what the heck they're going and avoiding silly mistakes which cause avoidable damage - a tall order, but not impossible.