I tried to rest between bigger areas or when my party was heavily bruised and I'm out of food. Food is quite nice source of missing HP as there is vast amount of it in the game. I use potions only during fights.
About spells, most of the times, cantrips are my main source of actions unless there is harder enemy that requires magic missiles or thunderwave. Also my cleric main focus is to heal whole team with lvl2 spell or single target when needed.
Constant camping feels like cheating, but there should be fatigue for not resting at all. In my first play-through I covered really big part of map without resting as I didn't even knew about passing time.
BG1, BG2, IWD shines here. You can clearly see and feel flow of time and know that your party needs to rest.
