It's important, then, to understand the category in some detail, because this will help one decide on the most pertinent and interesting areas to compare and contrast. Even if a teacher doesn't explicitly ask for such an evaluation, it's reasonable to give one provided it's presented with enough shades of gray. Anchor your judgment to facts. For judgments to be persuasive, they must be made on specific rational grounds. These reasons, of course, would have to be supported, not just listed.
Many arguments combine one or more of the methods just described.
Or s uppose you're writing an essay on how American cities changed over the course of the 20th century. You're likely to find it useful to combine definition, analysis and narration. Each of these categories would require definition, of course. A narrative order would then allow you to treat each of the categories in a natural progression, showing changes over time. You would still have to decide how to fit these methods of development into a single essay, of course.