Start with the form that ordinary usage would lead one to expect: an unemphatic statement, a particular tense, direct address or an explicit noun. Then identify the actual shift and the communicative gain.
For example, “هَذَا أَبُوكَ” (“This is your father”) may be said to someone who knows that fact but neglects its implications. The relationship is restated to awaken a sense of responsibility.
Not all departures have the same mechanism. Some alter the assumed audience state; others change the temporal form, pronoun, sentence function or response to a question.