That depends on you. About 50% of our students only buy one course or the other, while the other half buys both courses. Generally, students buy the "Complete Course" first and work through it. At the end of the course, they take the practice exam(s) included in that course. If they score high enough, they schedule their exam and don't buy the "Practice Exams" course. If they scored low, then they buy the additional "Practice Exams" course as additional practice before taking the official certification exam.