Interface
A good interface has your raid frames centred. It is very important to keep an eye on them as a healer. You also want to make sure that every bit of useful information is easy for you to see, for example keeping track of your cooldowns and when boss abilities will happen.
Disc Priest UI
The perfect UI looks very different for everyone, so play with something that you like and what you think works best for you.
Macros
Spirit Shell + Ascended Blast Macro
This allows you to cast Spirit Shell and Ascended Blast at the same time, which you want to do when you’re playing Kyrian disc in raid with Spirit Shell.
#showtooltip
/cast Spirit shell
/cast Ascended Blast
Ascended Nova Macro
When you press Boon of the Ascended, that button turns into Ascended Nova which can be a bit annoying to press, so what you can do is macro Ascended Nova to an ability you would not want to cast during your Boon window, such as Shadow Word: Pain.
What this macro does is cast Shadow Word: Pain (or Purge the Wicked if talented) without Boon active, and Ascended Nova when your Boon is active:
#showtooltip
/cast Ascended Nova
/cast shadow word: pain
Angelic Feather Macro
This Angelic Feather player macro places a feather on top of you with one button press.
#showtooltip Angelic Feather
/cast [@player] Angelic Feather
Mouseover macro
You can do any ability as a mouseover. You can replace Leap of Faith with any ability, and it will cast that ability on the target you’re currently hovering your mouse over. I personally have all my friendly targeted abilities as mouseover macros.
#showtooltip Leap of Faith
/cast [@mouseover,exists] Leap of Faith
Power Word: Barrier Cursor Macro
Casting Power Word: Barrier with one click. Casts Power Word: Barrier at your cursor location.
#Showtooltip Power Word: Barrier
/cast [@Cursor] Power Word: Barrier
Weakauras
The kind of Weakauras you use is very much a personal preference. Weakauras that work as a kind of all-in-one package are very popular such as Ablutions found at https://wago.io/V1QnPgivZ.
Outside of that, Wago has an amazing public library that you can browse: https://wago.io/weakauras/classes/priest/discipline