This will likely be the last Segment of the year. So let's make it through this burn-phase of the holidays with some cooldowns!
I mention an Addon called Power Auras. This addon has been around for a while. Even though there are basic Auras built into the default UI now, to alert you when you get an "On Chance" ability that happens, Power Auras allows you to decide what same or additional information you want to know, how it alerts you and where it alerts you. Maybe you want a big red identifier when your health drops below 40%, or maybe some easier to see indicators when other classes cast special abilities on you. Or maybe you would rather have them off to the side instead of right on your character.
By setting up your own custom auras you can make it phenomenally easier to know when to use your cooldowns in an emergency, but can also help you pace out your cooldowns to use 1 after another in succession, increasing your longevity over a greater duration, especially when you're receiving mitigation or reduction buffs from other players.
Most tanking cooldowns have a 3 minute duration or less. With this kind of availability you can use at least 1 of them nearly every group of trash mobs in dungeons or raids and really decrease your dmg taken (and healing required to keep you alive) so your healer can start healing those guys over there standing in the fire ;) .
In addition to Self alerts via visuals or audio indicators (or both), you can also have Power Auras alert you to Primary or Focused target buffs or debuffs, number of stacks, or a countdown for how long of a timer remains on it.
Allow me to wrap up with another addon which requires Zero setup, works with ANY class or role, extremely handy way to augment Power Auras or use by itself: In-line Auras.
This Places a small ticker, tracker and/or timer on any of your action buttons that have a HoT, DoT or use some kind of resource to build up an ability (like Combo Points or Holy Power). It will countdown your HoT/DoT ticks, tell you your stacks *right on the spell icon*. The advantage here is that there's no additional GUI hogging up your screen and you get the same information as other DoT/HoT trackers out there. One quick glance at your action bars and you know what's up!