Let me tell you what from my own experience you should be expected to do, and what somes player will expect things from you but which you can't/shouldn't do. As well as the difference betwin WAR & PLD
You did well to ask for advices, but I believe you did in the wrong place :3 as most people here will say "You should do that" instead of "You could do that."
1st, you're a WAR and not a PLD, there is a difference betwin both jobs, and if you are asked by random players (from DF or PUG) to adapt to their PLD friend gameplay, you have a right to tell them off.
Before I start to give you some advices I would like to describe the abilities one by one and give you some examples of situation where you can use them for a full effect.
Here are you tools to make/keep hate:
Defiance, when you are tanking it should alway be up, it increase your HP by 25% & drop your damage potencial by 25% "I know it sucks, but you're here to tank anyway." It also apply a full time bonus of 20% potency added to the cures you receive. The hate you generate is also increased dramaticaly.
In other words, there is no reason to not use it when tanking.
Overpower, while it seems incredibly weak (it is) its very usefull to take aggro on multiple target, this attack is also the 1st that will require you to place your mobs well, as it is conal. Be aware tho, its eating lots of TP when used.
Butcher Block combo, is the one with the higest damage potency & hate generation, before 2.1 it was used the most to be efficient, since 2.1 they increased hate generation with Defiance so people use it less. However you're free to use it more then you were told by others people if you want to have an optimal hate generation or if you want to deal more damage.
Storm Eye combo, is good when you have a PLD in the party as it will drop the resistance to slashing on its target by 10%, its also the combo next to Butcher block hate generation wise.
Storm Path Combo generate less enmity than the 2 others and give a debuff on its target, which will deal 10% less damage. Use it in solo, in situation where the 10% less damage can be life saver, or in endgame where you need to share hate.
Exemple: BC-turn 2, where you need to split stacks, you use SP as it will ease your PLD a little & not generate a big amount of enimity, our enmity generation being higer then a PLD in most situation, if you use butcher block the sphere will turn back on you instantly.
Steel cyclone, is for me one of the reason I started WAR, to see the dude in the CS charge the Garlemald soldiers & throw them away like piece of **** was amazing! /back-on-topic: It is very usefull because of its hate generation & doesn't really require any placement, you go in the middle, you pop it & you enjoy. Only cons, you will need 5 stacks of wrath.
Flash, is a cross class ability from GLD, costing alot of MP (251 @ Lv50) which make it unreliable (you will use it 3 time before getting drunk with ethers.) It is still usefull and can be on your barre. Being a cross class skill it wont apply blind when used by WARs. Its a 360° ability btw, which mean you use it in the middle of mob w/o requiring placement, alike SC.
Tomahawk, is used to pull, it cost alot of TP and doesn't generate as much enmity as others skills, use it once or twice if needed but don't abuse it unless you pull multiple targets.
Provoke, is another cross class ability from GLD, if you played FFXI you know the name of this ability, however FFXI provoke & FFXIV provoke are different. In FFXIV you use it when you lose hate directly to another player (DD or Healer) but using it on its own isn't enough as it will boost your enmity to the target temporarily (something like 1~2 sec.)
Basicaly when you use it you need/have to do a combo on the target to establish/re-establish your enmity. A good example again is when you share enmity with another tank in T2, when the other tank have 3 stack, you use provoke & do Butcher Block to make an instant max enmity generation. when you will have 3 stack the other tank will/should do the same.
Survival Tools:
Foresight, is the 1st one you get, it will raise your defense by 20% for a short period of time. I am not gonna tell you when you can use it as it may cause lots of disagreement here.
Inner Beast, will make reasonable damage, heal you for the exact same amount & will give you a buff reducing the damage you take. I personaly use it whenever its available on anything hitting hard.
Vengeance, will give you a counter-attack/ripost effect & give you a -30% Physical Damage Taken unlike foresight. Again, as I don't want to make/create a debate i'll let you figure out when to use it.
Convalescence, is again a cross class ability & is a must have. Increasing the cure potency received by a fair amount as well, its worth macroing with a /p & a <se.10> to say "Hey healer I used convalescence! Heal me now!" I personaly use it in "oh-****" situation, coupled with Foresight & Thrill of battle in the same macro. I say personaly because it is covinient to use that way for my own gameplay. Its not the way to go in 100% of the situations.
Thrill of Battle, is amazing from my point of view, increasing your max HP by 20% & heal you for the amount increase, it is also very usefull in "Ohsnap" situations, where it can save your life (Mountain buster/Death Sentance) come to mind, basicaly the more HP you get & the more its effective.
Bloodbath, give you back 25% HP back from an attack, needless to say that this skill is poor on its own, but it can be interesting if you macro it with either Vengence, internal release or Berserk, you chose!
Holmgang, is from my point of view a defensive skill in every situation, some WARs will tell you to not bother with it and its where I will allow myself to be critical and say that they are bad WARs, nothing more.
Before 2.1 it would bind you & the target, very usefull against Chirada (Garuda HM) & the Pudding Boss of WP (would save a life.)
Since 2.1, it will pull back the target to you and for its duration you're bound but invincible. Note that even if the target resist its effect you will still receive the invincible buff. (tested on KB in CT.)
Featherfoots, is a cross class coming from pugilist, while 15% evasion bonus seems minor but its very nice to have especialy in things like WP where you run with alot of monsters on your back. Alike Bloodbath, macro it with something else (Foresight?) to save space on your barre & increase the effect or unlike Bloodbath you can use it on its own, I personaly dont.
Mantra: My PUG being only Lv15 I don't know, but it seems to be decent.
Offensive skills, yes we've got a few. A shame that their duration is so low.
Berserk: Will increase your attack by 50%, but will give you a pacification debuff when it wear off. A way to use it is to put Storm Eye damage debuff on your target, then use Berserk and go for Butcher Block. <-- this is a simple example.
Now using it with defiance down or Unchained up: You can go for your storm eye combo again, then use your macro combining Berserk/Internal Release/Unchained if Defiance is up, no unchained if defiance is down & you chain with Butcher block.
Note; Inner Beast damage potency isn't affected by Defiance, the same goes for steel cyclone. I have some fun with SC during WP when i'm at the stairs leading to the Tomberry King, I pop these macros and go for rampage.
Note (2): I use a /p in the macro to remind the party about the pacification.
Unchained, use it when you plan to do damage while you're under Defiance, but be aware the effect is short (remain 20 secs.)
Internal Release, will give you 10% more chance of making crit damage, its self explanatory. (I personaly macro it with berserk and use said macro depending the situation.)
Mercy Stroke, is good in my book but you will rarely use it if you fight a boss on its own, because the DDs will want to take it down asap and in most case they will LB it near the end, so its more or less you call.
General talk:
Now for the global talk about WARs, most people will say that you "should" put 30 VIT in your stats allocation, allow me to say that you "should" do what feel the most confortable to you betwin VIT & STR.
I personaly have 20 VIT & 10 STR (for now), and I am looking to try to make a 30 STR to test it. STR will increase your damages and your parry % depending the cap you reach, this being said its better to look into STR when you start wearing a reasonable amount of allagan/AF Myths gears.
As an AF1/DL wearer its safer to look into VIT for now I guess.
Your tanking style will resolve more about spongeing damage with a big amount of HPs and will couple some damage mitigation (Inner beat/Storm Path/Foresight/Vengeance.) You will sometime be asked to drop Defiance to try and do some damages and to avoid taking hate (this happen when you DF titan/ifrit/Garuda HM as example,) a Top Tier WAR will have 6200+ HPs without defiance, don't be ashamed if you reach the 5500 as a secondary job.
If you ever try to speed run make sure to wear at least full DL with a relic normal or +1/equivalent, test with WP first, take 2 packs of mobs (the 1st 2 tomberys, the 2 birds and the beetles.) This is a good test.
If you can manage it & stay alive (assuming your healer know what he is doing as well) then you can start to look into it deeper.