The material at the AP level is not designed to "spoon fed" to you. Students will need to take responsibility for their learning. That means reading the assigned readings, but also taking the time to be sure you understand what you read.
During readings, be sure that you're taking notes that provide you a complete understanding. Be sure you understand the topic sentence in each paragraph and what each of the main ideas are that Strayer is writing about.
Balance is key. You should be working on learning at least a little bit of material for the class everyday. If you wait to do a ton of work the night before a due date, it is a lot less likely to be impactful, and it's guaranteed to be a lot harder.
They are designed to help you organize a lot of information. Take good notes, but be sure you can organize that information in a way that makes sense.
What are you doing to prepare for assessments? Be sure your notes are organized and you can recognize how the Learning Objectives relate to the Historical Developments.
The learning objectives are big questions, but by the end of the lesson, you should be able to articulate a response. If it's not clear for you, be sure you ask questions, or review until you feel comfortable.
This website has lots of good resources for preparation and reviewing. Use the resources that are right for you.
Arriving to class knowing where you need clarification helps you fill in the gaps in your understanding.