Diurnal and for bosses i tend to prefer to switch to Nocturnal, just personal preference. (Especially in Palace of the Dead)
Cleric stance but know when to switch it off, sometimes damage can happen quickly. So a party member could have 13K health and drop down to 5 or 6 easily at times as example and your heals are not worth much while in cleric.
As others have stated just start off for now perhaps as healing (not using Cleric) until you get more comfortable, with time you will get there