Break it up into manageable pieces. Take a break whenever you are not fully concentrating. This will help you to get a handle on how the chapter is organized, and what are the key points. You may even want to summarize a paragraph or two in the text, or in your notebook. Mark questions that you have about the reading and ask about them in class.
Chances are that several others had the same question.
Find out who else is in the class and ask them questions about the material and what might be on upcoming tests or quizzes. Another perspective can be very useful. Study groups can be very helpful too. Try to think about what the material means to you and try to apply it to yourself or the people you know. Your memory is greatly enhanced with this technique.