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.
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
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
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