Well, depends but for me it helped to jot down 2 contrasting things for ex: horrific monster & represents happiness (it is gooey and weak because happiness is a fickle fleeting thing). You can have three categories like: a feeling, a concept, a moment (ex in order: shame, a talking pillow, the day you got your first pet) and make a list of things in those three categories and mix and match them together in a way that isn't obvious right away OR lean into the obviousness (like happy, hero, friendship) and try to depict the details of that very precisely (so for our example it'll be developing the sense of humor of said hero and believe me you can go crazy there while still being within the bounds of a happy feeling with a hero concept with a friendship moment)