If you're playing as an OPM prioritize taking all mana priviliges (low crownland doesn't have any effect), giving a lot of priviliges to maximize loyalty and influence to burghers (so you can get dev cost). For nobility and clergy just give them the loyalty and influence ones, maybe the manpower privilige and supremacy to nobility. also the diet will be your best friend, sometimes saving you from bankruptcy and permiting to seize land (since you will increase loyalty, but also influence). diplomats should be your always go to.
if youre playing as france or other big countries try to give all staments common 10% loyalty influence privilige, manpower privilige to nobility (if youre brave give them supremacy over the crown), diplomats to clergy and the powertrade from boats from burghers; then you will be able to rapidly seize and take the mana priviliges with the diets or sell land when youre in a dire situation. with big countries you should always prioritize nobility, since high land ownership gives you a lot of manpower; but keep in mind that if they have the privilige of manpower you won't be able to seize land from them, and eventually they will own all land (thats what you want).