Don't confuse with diào. If the verb means 'adjust / mix / mediate / season / flirt,' it's tiáo (
调整,
调料,
调情). If it means 'transfer / investigate' or refers to a tone/melody, switch to diào (
调动,
调查,
音调). Trap pair:
调皮 (mischievous) is tiáo, but
调子 (melody) is diào.