I agree with Steven, Additionally I recommend reviewing these processes throughout the PMBOK Guide and Flashcards for this area. It is about repetition at this point. Stay with it, it will get better.
Planning is a difficult process group because there is so much involved in setting up a project. I highly recommend that you go over your study plan, look to see what you are weak in (particularly by taking simulated exams and quizzed within the Exam Simulator), and work daily to correct those mistakes. If you need a fleshed out study plan, you can take a look at my generic one here:
www.amazon.com/Setting-Your-Exam-Study-P...rds=steven+mudrinich
. Best of luck in your studies!
Training for Project Management Professional (PMP)®, PMI Agile Certified Practitioner (PMI-ACP)®, and Certified Associate in Project Management (CAPM)®