Keep Renewing Mist Rolling
Renewing mist is core to our spec. Nearly everything in our talent tree synergizes with it, and you should aim to keep 5 up at all times on all allies in a M+ environment.
Pair Cooldowns w/ Boss Mechanics
Practice makes perfect, and being able know the damage before it comes really helps smooth things out. Try and get boss timer to know when a specific ability is going to happen, then pair a cooldown of your own to offset it.
Use Procs
Spread your healing with things like Zen Pulse, Vivacious Vivification, and Strength of the Black Ox. Reacting to these procs and significantly increase your HPS.