I have no insider knowledge of shortcuts guaranteed to score a 5, but for additional prep and review, the AP website and Kahn Academy are popular choices.
AP - https://apcentral.collegeboard.org/courses/ap-computer-science-a/exam/past-exam-questions
Kahn Academy - https://www.khanacademy.org/computing/ap-computer-science-principles/ap-csp-exam-preparation