Shield Oath, have it up all the time.
The only real reason you could have to not have Shield Oath is if there is a second tank and you're not gonna be tanking.
Flash a lot, at least 3 times, and Circle of Scorn is off the global cooldown and should be used between Flashes.
For bosses, use the Enmity combo, Fast Blade -> Savage Blade -> Rage of Halone.
For tankbusters, now that PLD can block magic damage as well, Sheltron (or Bulwark).
And if you notice you are losing aggro on a mob, start doing the enmity combo on it.
And a general note, outside of Savage or Extreme, you shouldn't worry too much about your damage as a tank, that's the DPS job. Just focus on enmity and surviving.