Sep 12th 2010 2:01PM I actually did the same thing as you did, in that I rolled a DK in Wrath after playing 2-3 years as a mage. Thankfully, I also had my mind set on making him a tank to learn how to play the role, as I have previously played Melee DPS (a Rogue) when I first started WoW.
As people have mentioned, starting to learn how to tank was rough - people dying constantly, the nerd rage, etc. But if you put forth enough time to learning the role you'll eventually get into the groove of tanking, as I did.
A great mob to try practicing threat building and cooldown management on is Torseg the Exiled in Storm Peaks - He has a fast respawn timer, uses a lot of stunning and knockback attacks, but he doesn't hit particularly hard on plate. If you can efficiently and consistently kill him in a tanking spec, you should be a little better suited to tanking (although it's not a good practice tool for AoE tanking).
Apr 17th 2010 3:20PM I still enjoy spellstealing the Aura of Arcane Haste buff whenever i run H-Nexus. It gives you stupid amounts of haste and SP, and the rest of the party benefits from it too! (though to a lesser extent)
Mar 27th 2010 5:05PM #showtooltip Polymorph(Rank 4)
/castrandom Polymorph(Rank 4), Polymorph(Pig), Polymorph(Turtle), Polymorph(Black Cat), Polymorph(Rabbit)
This macro is purely cosmetic, but I still like it nonetheless. When you cast Polymorph on the target, it randomly selects the Polymorph spell it uses from the ones you know. Makes it a little less boring than just the same one every time.
Feb 23rd 2010 9:48AM Although I have the bragging rights now for getting it, I'd say wasting 8 months of my life grinding for the Insane in the Membrane achievement.
Jan 23rd 2010 1:55PM When we were still doing Ulduar in our weekend raids, we concluded that anyone who was unfortunate enough to fall off the edge at the start of the Kologarn fight fell victim to his "Third Arm".
Jan 14th 2010 8:10PM I've always wanted to see a CoT: Battle of the Shifting Sands (fending off Infinite and Qiraji to ensure the original closing of the Scarab Wall), but the odds of that happening are pretty slim.