To be able to play a healer well you need a good UI and especially good raid frames.
WeakAuras - An amazing addon mainly used to track cooldowns and procs.
BigWigs - Extremely useful for raiding to know when certain encounter abilities occur to plan your gameplay around.
Grid2 - I personally use grid2 but any configurable raid frame addon will do the job if you put in the time to customise it.
Important things to track are as follows:
- Other raid cooldowns
- External cooldowns
- Absorbs/healing absorbs on raid frames
- Personal defensives on raid frames
- All relevant raid debuffs on raid frames
- Cooldowns of other healers' dispels
- Duration of your own spells/abilities on raid frames
I'm sorry to say that I don't have any weak aura's that I wish to publicly release at this time, however I've been told the Resto Druid Discord channel is a great place to get some neat weak aura strings so I would do a search for that!