TL;DR incoming, sorry.

Pretty much, the way you'll want to pull is with Outbreak, unless you're trying to pull a caster- then Death Grip, otherwise they'll just stand at range at cast at you (if Death Grip is on cooldown, you can also Strangulate and Icy Touch to get them to run at you). I generally pull from a fair distance and toss a Death and Decay with me at the very far edge, so they have to run through it to get to me. That gives it an extra tick or two. If you're in an AoE situation, hit Pestilence to spread the diseases around for the debuffs and threat. Dark Command shouldn't be used to pull, because you'll want that available if something goes running for the healer. Dark Command won't help you if you're already established aggro.

Blood Boil only if there are more than three things, since it's mainly only good for threat and hits like a wet noodle. Otherwise, Heart Strike, since it cleaves up to three things (the positioning is that they have to be in front of you, but this isn't hard). The cleave from Heart Strike is generally enough to hold something unless the DPS is going berserk and just attacking a target other than your main one. If you absolutely only have to hit one thing, blood strike, but I don't have to use it too often.

The thing you want to do is keep your blood runes on cooldown so you get the Blade Barrier buff (6% damage reduction). If you can, use Rune Tap when you're below 90% health to spend one of those runes. There's no real incentive to not use Rune Tap when you're below 90%, as the cooldown will reset and the tap will be free when you hit 35% health if you talented into Will of the Necropolis (and if you didn't go do so now it is an amazing talent). I also generally hit Bone Shield before each pull and then again if there's heavy damage going out and my Blood Shields are getting torn through too fast.

From there, Death Strike for healing and a shield, and Rune Strike if you need threat or if your runic power is getting high. Once you get into the swing of the fight, the rest is just juggling survival cooldowns as needed in addition to spending blood runes and Death Striking. Anti-Magic Shell is fantastic and will also generally save you from standing in bad (it's hilarious on Argaloth. I rarely have to move much). Bone Shield, again, for heavy damage phases. I use Vampiric Blood when my health dips a bit low, as the cooldown is fairly short, and try to time it before I hit Rune Tap, as the additional healing applies to that, death strikes, and pretty much any healing source (even bandages. >_>).

Horn of Winter no longer gives additional dodge, but it will give parry because of the increased strength. That, and it will also help your group down things faster.

I also spec into Endless Winter just so I can mind freeze when I need it. Interrupts are definitely a thing, and I rarely trust a PuG to handle them. I'd rather be able to do it myself if need be. XD If you're okay with pooling Runic Power, I'd suggest speccing into Lichborne, and making a macro button for Lichborne and Death Coiling yourself.

And when you get into heroics, don't be afraid of CC. Using it is faster than wiping on trash because you didn't. When you first get started, you'll generally need it, but as your avoidance and mastery go up you can start using less and less. Too many tanks (even fully T11 ones) waltz into a dungeon and decide not to use CC and then die really fast. Less damage on your means you're less likely to die from damage, and also less of a chance the healer will go OOM trying to spam expensive heals to keep you up.

And the healer is your friend (90% of the time). Their blue bar is your green bar- always keep that in mind.

Otherwise, stats are up to you. Do you rather have mastery, or avoidance? Both are generally equally as good, but if you go with mastery, you'll want a little bit of hit and expertise. Not hitting the 8% cap, but I find that hanging at around 4-5% usually works. Because of Veteran of the Third War, you can generally reforge most of your expertise and still wind up with a good number.

And always use a strength two-handed weapon. One with Mastery is best (even if you don't stack it). There are one-handed tanking runeforges in there. But those do not exist to you now.

OKAY I AM SORRY THAT IS A LOT. And you probably already know a lot of that, but. D: That's how I do things. I also /flex a lot, because that's a very important buff to bring with you (I've specced into Abomination's Might and that talent will forever look like a flexing dude to me).