Keeping an exercise log, even for a little while, can go a long way toward strengthening your fitness practice. Exercise journals help you set goals, measure progress, stick to a fitness program, and plan improvements. It should include: Date, time, Location, Instructor, Type of Workout, Duration/Intensity, Focus, How I felt Before, How I felt After, My Workout Notes, My Future Goals.
If your question is how to prepare one i.e., how should it look in terms of form and content, I guess you have to draw from your personal and professional experience to determine what would be valuable information. For example:
-What are the basic concepts and movements one must master before moving forward? And how would you take a beginner on that journey?
-How do you track progress; is it more than just number of repetitions?
-How do you know when and/or how to increase movement complexity?
-What is a reasonable amount of time to expect change or improvement e.g., each session, every week, every month?
-What is the person’s reason for choosing Pilates? e.g., does she have a specific goal or need that only Pilates can satisfy?