Program decomposition is essential for developing maintainable and efficient software, yet it remains a challenging skill to teach and learn in introductory programming courses. What does program decomposition for procedural CS1 programs entail? What steps do CS1 students need to take to improve the decomposition of their programs? What scaffolded exercises can instructors use to teach program decomposition skills? We aim to answer all these questions by presenting a conceptual framework that (1) is grounded in the established code style principles, (2) provides a systematic approach that can be taught to students as an actionable strategy to improve the program decomposition of their programs, and (3) includes scaffolded exercises to be used in classroom activities. In addition, the systematic approach is highly automatable and can further be used to implement visualizers, automated feedback generators, and digital tutors.