All of rhetoric can be encapsulated by the three rhetorical appeals, described by Aristotle in The Art of Rhetoric. These appeals are depicted in a triangular diagram where each appeal rests at a point.
Each corner of the triangle is a categorical point of consideration: ethos, logos, and pathos. Speaker, message, and audience mix together to form an occasion in the context of time and place. This then set the boundaries of what is judicious for a given speaker, message, and audience.
For Writing or Speaking:
Use the rhetorical triangle to help plan your essay. You generally spend the most time on logos, thinking of the structure of your claim, your reasons, and what evidence you can bring to bear. But considering ethos and pathos can make the difference between a powerful persuasive act and a simple recounting of platitudes.
For Reading or Listening:
Consider the occasion and audience prior to analyzing the appeals. If not provided, infer from what is stated in the text or performance. Draw the triangle and jot down any word, phrase, or detail that categorically fits with the appeal. Scan the text or listen to the media twice if possible. Once you have your notes, search for a pattern, a preponderance of words, syntactical structures, devices, or writing modes.