Enmity GearFollow

+Enmity is a multiplier for ANYTHING that generates enmity (which again, is basically anything you do). Your only decision is whether you could potentially generate more enmity for a given action with a piece or set of pieces that give you something else. For example, a sea gorget for Atonement may or may not give you more total enmity than Ritter/Harmonia (personally I'm pretty sure sea gorget is marginally better).

In summary, macro in +enmity gear for all your hate tools, but some hate tools may be best served by a +enmity set with a piece or two swapped out for equipment that benefits that particualar move more.

To add to what Fisban said, specifically:

For Flash, load up on any haste you have. W. Turban + Dusk hands/feet is a great start (pricey, sure, but a great start). Homam is an awesome thing to work towards for PLD. Aurum has some decent haste options. The goal here is to shave your recast down as close to 23 seconds as you can get it. Once you've hit the 23 second timer, then load enmity on instead. More frequent flashes means less times you're being hit and more enmity build up.

Other spells are similar, but not as important. Cures... you shouldn't be riding the timer on these, so Enmity makes a little more sense here. It's also why I carried a Hospitaler's Earring - bigger cures = more enmity generated.

Haste will do nothing to job abilities, so you'll want to maximize enmity as much as you can here. The level 68 Iron Ram set is an awesome place to start. Other options will open up as you get there.

As mentioned, when Sentinel is active, your enmity modifier for everything you do becomes capped. No enmity gear will even remotely affect anything during that 30 second period. But, even merited, it'll only be active 30 seconds of every 4 minutes and 10 seconds, leaving just over three and a half minutes where you'll want enmity gear to help keep you topped off.

To clarify a little bit, macro as much Enmity as you can into actually using Sentinel (No Enmity during it's duration, but as much macroed into actually using the JA helps increase the Enmity gained from using it).

Beyond that, macro as much Enmity as you can into Rampart. (Or have 2 Rampart setups, one with max Enmity you have for hate purposes and one with max VIT you have for survival purposes).

Macro as much Enmity as you can into Shield Bash (Or if you're anal like me, I macro in Shield Bash + gear, then Enmity)

Macro as much Enmity into Cures as you can, and always cure in a Hospitaler Earring. A full Cure 3 or 4 with a Hospitalers generates more Enmity than the same thing with a Hades+1 in place of a Hospitalers.

Macro as much Enmity as you can into Atonement (Assuming you have it, if not just work on obtaining it as you can, it's a great WS to have available)

Like it was said before, you're generally better off macroing Haste and Fast Cast into Flash, then Enmity everywhere else. Exceptions apply when you have Haste and 2 March and a ton of Haste gear, but Fisbans calculator can answer those questions.

I have 2 Flash macros, one when I'm receiving less than Haste and 2 March and one when I'm getting all 3 things. My first setup has 19 Haste and 2 levels of Fast Cast, and 25 Enmity (Including merits, not including Dorado Sushi or a Main weapon slot). My second only has 14 Haste and one level of Fast Cast, but 37 Enmity (Again, not accounting for Food or a Main weapon).

The first setup is actually better unless you can still cap your recasts with the second setup. More Enmity with a higher recast is worse than less Enmity with a lower recast, for any fight lasting long enough to warrant a dedicated PLD tank.

One trick that I do that helps, is macro all my Haste and Fast Cast gear into Reprisal. Cutting that recast down helps you keep Reprisal up more often, resulting in a higher Shield Block rate for more of the fight, for minimal effort to write a quick macro to do this.