If your upcoming Brave New World test has a multiple choice section, then here are some suggestions on what to focus on while you study.
Be sure to understand each major character's roles in the novel and their contributions toward the plot or conflict. To aid your studying, I recommend making a notecard for each major character and including bullet points of some of their major actions or contributions as well as including details on their appearance or characterization by the author.
I would definitely make note cards for Bernard, Lenina, John the Savage, Linda, Mustapha Mond, and Helmholtz Watson.
Key Plot Events:
Make a thinking map or graphic organizer (like a flow chart) to help you track all of the major developments in Brave New World. Focus on understanding the big picture, but be sure to include events that relate to character development or conflict.
One tricky thing about Brave New World is all of Huxley's clever new names for the technology and lifestyle items used byt the characters. I would make flashcards for these as well, just to make sure you keep all of the different names for things straight, like: Our Ford, Soma, Obstacle Golf, Feelies, Decanting, World State, the different classes--Alpha, Beta..., Savages, to name a few.
*I also recommend the very good practice quizzes on eNotes for reviewing the chapters.