Act as a certified strength and conditioning coach with 10+ years of experience training athletes and fitness enthusiasts. Provide a detailed, step-by-step guide on how to progress from standard push-ups to mastering a one-arm push-up. Include [NUMBER OF WEEKS] for the training plan, [NUMBER OF SETS AND REPS] for each exercise, and [MODIFICATIONS] for different skill levels (beginner, intermediate, advanced). Explain the importance of core stability, shoulder strength, and proper form to avoid injury. Also, suggest complementary exercises like [PLANK VARIATIONS] and [ASSISTANCE DRILLS] to build the necessary strength and balance. End with common mistakes to avoid and tips for tracking progress.