It costs 1,000 Gold, which can be a hefty sum for some players, but aside from the costs involved in your epic mount training, it will be the best 1,000 Gold you'll ever spend. Paladins are a hybrid class, allowed the wonderful opportunity to experience the three core roles in the game - tanking, healing, and DPS. The only other class that can do that are Druids (who, for that matter, should also spring for dual specs). If you don't get dual specs, you're not making the most out of your Paladin.
It doesn't matter what specs you choose, although arguably you will get the most bang for your buck if you spec for different roles. The most pragmatic players will elect to go Protection and Holy, which practically ensures a raid slot in every raid. Others will have a raiding spec and another for PvP, or maybe just a spec that allows them to do the daily grind more efficiently. The point is that having dual specs allow players to experience the game completely differently on the same character, and it's all accessible with the click of one button. I'm sure you don't need any more convincing, but it's never a bad thing to plug an old post, especially one where I discuss dual specs for Paladins.
4. Become a Crusader
Is there really a more fitting title than Crusader for a Paladin? It's every bit as cool as the Guardian of Cenarius Achievement for Druids, something I know more than a few Druids spent mind-numbing days in Silithus to obtain. The Crusader title is so perfect for Paladins that any other class sporting it almost deserves a snicker and a look from head-to-toe. It's also pretty easy to obtain considering that Blizzard has made it phenomenally easy to suck up to a faction.
By the time you hit Level 80, you should be Exalted with one or two factions within the Alliance or Horde, and it should be easy enough to raise the rest as low-level quests grant the same reputation. Once you're exalted with all your factions sub-factions, doing the Argent Tournament dailies should be a cinch. It will take some time to complete, but slow and steady should do it. One other thing is getting to exalted with the Argent Crusade, although a tabard and some heroics should do the trick. This, combined with the Ambassador Achievement should result in your Paladin proudly bannering the Crusader title.
As a corollary, any Paladin worth her salt would be chummy with the Argent Dawn. If you're Level 80, run Stratholme or Scholomance over and over. Consecrate. Divine Storm. Blow all those filthy undead to kingdom come. The Argent Dawn are the thematic faction for Paladins, and getting exalted with them as well as the Argent Crusade will also unlock The Argent Champion. This means you get the Argent Crusader title, which is also very Paladin-y, but doesn't have the elegant simplicity of Crusader.
5. Bubble hearth
No, really, bubble hearth. Do it with pride. It is one of the defining actions of the Paladin class which gets undue ridicule from other classes. But the truth of the matter is that if those other classes could do it, they would. Paladins are the one class with the ultimate 'OH $#!%' ability - we can escape from virtually any situation with the Divine Shield + Hearthstone combo. Shamelessly create a /castsequence macro for it. Heck, append a nasty emote, too, if you like. Bubble hearth is so iconic that Blizzard made it into a toy.
It's even more powerful now, with the cooldown on Hearthstones slashed down to 30 minutes. It will get you out of trouble, save you from repairs, and generally help you squeak past some really tight situations. I'm sure everyone who has played a Paladin long enough knows this and has already done it. All I'm trying to say is that it shouldn't be a point of shame! Be loud, be proud, you bubble hearther! Just for kicks, run into the heart of a enemy's major city and cause some mayhem. Then bubble hearth. Just make sure there aren't any Priests or Warriors looking your way.
There you have it, my top five list of things you absolutely have to do as a Paladin. Of course, there really isn't anything you have to do in the game. It's an MMO, so you can play it however the heck you want. It's just that there are a few things in the game that make playing a Paladin a much richer experience. If you've got your own ideas, throw them our way in the comments below. Until next time, Crusaders!