The kind of expressions of approval that are not manipulative are the ones that bubble out of you without any forethought. Anytime you are wondering if what you were planning to say might be coercive approval, it probably is. Is what you are saying the kind of thing you would naturally say to an equal, a friend, or your boss, say? Or does the idea of saying this to your boss seem highly inappropriate?
Expressions of approval are inherently manipulative the approval is designed to manipulate the child into meeting your own standard.
Many have suggested that my use of the word ‘coercion’ is non-standard and that I should find another word, but I think that is the quest for a euphemism. People don’t like using a harsh word for something they think is morally right. But if you prefer, use the word ‘manipulation’ instead—as long as it is clear that manipulating children is not taking them seriously either.