So talk to me about holy priest

[Kokolums]

I bought the 120 loom upgrades for the cloth set and then chained wrath timewalking as holy priest over the weekend to 120. I slowly learned some of the basics of holy priest healing as I went. This is what i have so far for party healing.

1. I'm talented as 2221113.
2. I try to keep prayer of mending on cooldown and try to cast it on someone not already affected.
3. If there's nothing else to do, I put renews on all party members.
4. If there's gonna be a lot of party wide damage, cast power word: Salvation as my ultimate heal.
5. Just keeping renews on everyone and having 3 prayers of mending bouncing around is another strong way to party wide heal.
6. A lesser party wide heal is renews on everyone and spam prayer of healing.
7. Single target is spam flash heal and hit them with holy word: serenity when its off cooldown, maybe cast guardian angel on tank if needed.
8. If there is probably too much incoming damage early in a pull, use psychic scream to CC the pull for a little bit to get more control.
9. If there is just too much damage, let 2 DPS die and keep up tank and the best DPS as a last resort.

I'm sure I'm missing a lot or doing things wrong, so any feedback would be good.

[Clozer]

Renew is kinda weak. Didnt cast it once in whole Legion - it was buffed but still it's super weak. Don't use it all except your are moving. You are always better off using heal.

Icyveins got it pretty good:

Holy Word: Sanctify when a cluster of your raid is injured.
Holy Word: Serenity on an injured ally.
Circle of Healing on cooldown when at least 4 allies are injured.
Prayer of Mending on cooldown.
Halo when most of your raid is injured.
Flash Heal for emergency triage on an ally near death.
Prayer of Healing for general purpose raid healing.
Heal for general purpose single-target healing.
Renew while moving and emergency healing is required.
Smite an enemy when no healing is required.

[Nzete]

For 5 man groups, I'd recommend 232212(1 or 2).

Holy priests have no movement abilities other than feathers.
Having chastise as a stun is amazing. Damage that isn't done to the party is damage you don't have to heal.
Benediction is down to at 25% chance to leave a renew. Halo is a no go for dungeons (you pull every mob in the dungeon or close). I've been using divine star.
Holy word: salvation is godly in a raid setting but really isn't as good in a dungeon setting. I mostly use Light of the Naaru because Apotheosis is a dead global before you can put out any healing.

For reference, these are my mythic+ talents. I am choosing them to provide movement (feathers, moving on surge of light proc globals) and to synergize with my azerite (promise of deliverance) where I'm using holy word: serenity as much as possible. I usually have holy word: sanctuary if I need aoe healing beyond prayer of mending and alternating flash heals (trail of light) with the tank for the spot healing. Note that you can easily have your tank die while channeling divine hymn. It is probably worthwhile to use guardian spirit on the tank if you need to commit to a divine hymn channel.

Extensive flash heal use in dungeons requires a large stash of beverages (and mana potions) and drinking like a lush every time the tank drops combat (not quite as much drinking in leveling dungeons). Use your hymn of hope during in combat RP.