There is no real pawn string for healers. the best you can do is find weights based off of how you heal. There are tools out there for most healers to generate weights. For shamans we have Splashy Stats from Chainheal however even this is just a suggestion.
Healing like Tanking is almost impossible to place weights on. Some times the problem is you just need to heal for more per cast so crit or mastery would be better. Some times the amount your healing for is fine but your heals are going out to slow and you need more haste. or maybe your having mana problems and need to pick up some more crit.
I find it best to hover around 100% mastery then get enough haste to where you feel good and then get crit. If you are raid healing with other good healers you can drop haste as you wont need to get emergency heals out as much. I have my haste kinda high because we are 2 healing heroic with ~16 people and i find the need to spot heal a good bit.
Unable to post armory link since im kinda new here but you can search for me on US Azjol-Nerub character name is Naidea