To improve your grades in the NPTEL course "Introduction to Turbomachines", focus on mastering the fundamental principles of turbomachine design, performance, and application. Develop a strong understanding of thermodynamic analysis, fluid mechanics, and mathematical modeling. Practice solving numerical problems and case studies, and review video lectures, notes, and assignments regularly. Pay attention to key concepts like turbine and compressor design, pump and fan performance, and efficiency optimization. Participate in discussion forums, clarify doubts with instructors or peers, and attempt previous year's assignments and exams to assess your knowledge. Additionally, work on visualizing turbomachine components and processes, and apply theoretical concepts to real-world engineering scenarios. By staying consistent and persistent, you'll see improvement in your understanding and grades in the NPTEL Introduction to Turbomachines course.