1)Ensure you attend all the classes from the online portal where you are planning to get the 35 PDU's.This will give you a base to start preparing for the PMP Exam.Please note this might not be applicable for everyone as it depends on how you plan to earn the PDU.

2)Start with HeadFirst PMP and try to complete the book,it's easy to understand the concepts.The authors have written the book in the most descriptive manner.