仔细 (zǐxì) means 'careful, attentive, meticulous' and focuses on the thoroughness and attention to detail in how you do something (e.g., checking, reading, writing). It's broader than 细心 (xìxīn, 'attentive to details'), which emphasizes a person's careful nature, and less formal than 谨慎 (jǐnshèn, 'cautious, prudent'), which implies wariness to avoid risk.