How comfortable you are with your tanking ffxiv skills

First, what accessories you use should depend on your healer, and how comfortable you are with your tanking skills. If you can afford them then yes, Crafted i150 pentamelded accessories are the best, but they tend to be rather expensive. Personally, unless the healer says something I go with full slaying now. If my healer wants me to have more HP, all he/she has to do is ask and I'll swap - I have a "Savage" set that's 2 Fending + 3 Slaying and provides about 16k HP and a 4F/1S set that gives me close to 18k now.

Second, before you decide on how much to pull for a dungeon overall, do the first pull - the entire first island in Neverreap, or the entire first room in Fractal - and judge what to do from there. If the mobs die extremely fast and your healer is at least decent, max pulls are probably a go. If the speed is decent, but not stellar, double pulls at most. Slow dps? Single pulls unless you think someone's gonna try to pull something for you to "speed things up" (hint: pulling for the tank usually doesn't speed things up, and it can piss the tank and/or healer off). As an aside to this, I almost always pull the entire second room in Fractal as well, but that's mainly because that one consists of 2 bigger mobs and a bunch of "light trash" that dies really fast to any AoE, even my own.

Finally, my MO on any pull with 3 or more mobs is something like this: Unmend -> Plunge -> Unleash -> (run to where I'm gonna tank, unleashing packs as I run by them) -> Unleash + Shadowskin + Blood Price -> Unleash (or Abyssal Drain if there's enough incoming hits to support it) repeatedly until Blood Price drops, using Salted Earth, Reprisal, and Low Blow (in that order) as well during this time. When Blood Price drops, It's a good idea to pop Dark Arts + Dark Dance and Dark Arts + Dark Passenger (if using unleash, you might pre-prep the first DA a couple of GCDs in advance so that you can do DD->DA+DP), then go into your single-target rotation on the most dangerous mob still standing, or whatever's health is lowest if none are any more dangerous (I admit, I'm not very good about popping DA+DD or DA+DP at that point, tho).

With the above opener/rotation, if incoming damage is still too high with just shadowskin, I might pop Awareness, Foresight, or even Shadow Wall for more mitigation, and I might pop Convalescence as well to increase incoming heals. Always save DA+DD and DA+DP for after Blood Price drops, tho - you don't want mobs to miss while BP is up, you want them to hit you for low damage so that you get MP from it. The only thing that can throw a monkey wrench into the machine is a holy-happy WHM. If I get one, I usually ask them to wait for me to swap to my single-target rotation to spam holy. If they refuse, I'll make due...Holy's a lot of damage and mitigation, and is gonna get the dungeon done faster, but you have to watch your MP more closely if your WHM doesn't feel like cooperating with you.