So your out judgin' crimes and having a good old time and you hit level 10, time to pick your only specialization till you get a second one at 30. What to pick? Well theres a few things you need to know.
Paladins get their first real healing spell (Flash Heal) at 16. That means Holy is out the window till then. Holy Shock is nice but its cooldown makes it of limited value and honestly the whole shockadin thing for leveling is just slow and painful.
This leaves Retribution (Ret) and Protection (Prot). Now Blizzard really Jumped the Shark with this one.
They have said they removed Divine Storm as defining ability because they dont think you should have an AoE this early, yet those statement ring hollow when you compare it to Avengers Shield effectively a ranged AoE attack. So...you guessed it for leveling Protection is better than Ret, and heres why.
As Ret you gain 30% Attack Power as Spellpower, so your judgements hit a smidgen harder. You do 20% more damage with 2-h weapons, small at this level, and when you judge you get mana back...yay. Their 'signature' ability of Templar's verdict takes a minimum of 7.5 seconds to power up to 3 charges and they aggressively focused on making sure 1 or 2 charges hits like a feather.
By Comparison Prot gets its ranges upto 3 target shield throw, 30 yard pull, hitting like a truck at low levels. Additionally it silences what it hits so you can pull casters back to you if your having problems with them. Your spellpower is increased by your strength, 60% of it, so easier to raise than Ret's. When you Judge you get 5% more mana back than Ret -still lackluster for a long time. You gain 15% stamina. Finally a big thing is that every time your hit you gain 5% of the damage as a stacking Attack Power buff. So a hit for 20 damage gives 1 AP and so long as you keep fighting it keeps stacking up.
So yes, grab yourself a shield and use it to pound people flat.
Talents At 10, 11, and every odd level after you get +1 talent.
10, 11 = Seals of the Pure +2 for +12% Seal damage
(If you plan to try tanking)
13, 15, 17 = Divinity +3 for +6% healing effectiveness on you and by you.
(For more soloing)
13, 15 = Eternal Glory +2 for a 30% chance your heal wont consume holy power.
17 = Divinity +1 for +2% healing effectiveness on you and by you.
19, 21, 23 = Toughness for +9% armor
25, 27 = Judgements of the Just to slow attackers attack speed by 20%
29 = Hammer of the Righteous a beautiful AoE attack for 1-h weapons that hits nice and hard.
Another thing to note is that when your Prot you are INVINCIBLE. Just make sure to keep them in front cause you cant dodge, block, parry whats behind you.
Now a special note on Ret vs Prot on leveling. Generally speaking Heirlooms push Ret up to where its more viable, because their like having some of the best blues all the time. But if you don't have them Prot wins hands down.