ISRO (Indian Space Research Organisation) and DRDO (Defence Research and Development Organisation) are prestigious research and development institutions in India, and securing a job there is highly competitive. Here's a general outline of the steps you can take:

1. Complete Your BSc/MSc with Strong Grades:

• Focus on relevant subjects: While your current subjects might not align directly with ISRO or DRDO's core areas, strong grades and a solid foundation in science can be beneficial.
• Consider additional courses: Explore opportunities to take additional courses or certifications related to space science, engineering, or defense technology.

2. Prepare for Competitive Exams:

• ISRO Recruitment: ISRO conducts various recruitment exams, such as the Indian Space Research Organization Centralized Recruitment Board (ISRO-CRB) exam, for different positions.
• DRDO Recruitment: DRDO also conducts various recruitment exams, including the Defence Research and Development Organisation Scientist Entry Test (DRDO-SET).
• Prepare thoroughly: Study relevant subjects, practice mock tests, and improve your problem-solving skills.

3. Gain Research Experience:

• Internships: Look for internship opportunities at research institutions, universities, or even within ISRO or DRDO itself.
• Projects: Work on research projects related to space science or defense technology. This can help you develop practical skills and knowledge.

4. Network and Build Relationships:

• Attend conferences: Participate in conferences, workshops, and seminars related to space science or defense technology.
• Connect with professionals: Network with individuals working in ISRO or DRDO. You can connect through LinkedIn, professional organizations, or academic conferences.

5. Tailor Your Resume and Cover Letter:

• Highlight relevant skills: Emphasize your technical skills, research experience, and academic achievements that align with the job requirements.
• Customize your applications: Tailor your resume and cover letter to each specific job posting, highlighting how your qualifications match the requirements.

6. Prepare for Interviews:

• Research the organizations: Learn about ISRO and DRDO's missions, projects, and values.
• Practice common interview questions: Prepare answers to common interview questions and practice your communication skills.

Remember, competition for jobs at ISRO and DRDO is intense. Consistent hard work, dedication, and a strong academic foundation are crucial. Keep yourself updated on their recruitment processes and deadlines.

I hope this information helps you.