Good question! It is advisable to read the passage twice, maybe even three times, to ensure you do not miss any details that could help you form an argument. While you are reading, look for interesting stylistic patterns, repetitions of themes, or references to other parts of the text. If none of those things are in play, you can still look at the language the author uses and consider how it might compare to or depart from other parts of the novel. (Hint: Check in other parts of the work).
If you are dealing with a descriptive passage of a particular setting, for example, you might think about how the physical space of the story affects the movement of the characters. Are they trapped in a small space that keeps them constantly colliding and conflicting with one another? Are they in the middle of the desert where the openness of the landscape leaves them feeling isolated and alone? Asking these kinds of questions while you read will help you to not only decipher what the text is saying but also to understand it from several different angles. Then, once you are through this stage, you might decide to incorporate some of your own outside knowledge or insights if you feel they are applicable.