Preparing for the UPSC prelims in 3 months can be a challenging task, but with a systematic approach and dedication, it is possible to cover the syllabus effectively. Here's a detailed plan to help you prepare for the UPSC prelims in 3 months:

1. Understand the Exam Pattern and Syllabus:
- Familiarize yourself with the UPSC prelims exam pattern, which consists of two objective papers - General Studies (GS) Paper-I and Civil Services Aptitude Test (CSAT) Paper-II.
- Go through the syllabus for both papers and make a list of topics to cover.

2. Create a Study Schedule:
- Divide the available time into 3-month blocks and allocate specific time slots for each subject and topic.
- Ensure that you cover all subjects and topics within the given timeframe.

3. Focus on NCERT Books:
- Start your preparation with NCERT books from classes 6 to 12 for subjects like History, Geography, Science, Economics, and Polity.
- These books provide a strong foundation for understanding the basic concepts.

4. Refer to Standard Textbooks:
- Once you have covered the basics, refer to standard textbooks recommended for UPSC preparation.
- For subjects like History, Geography, and Polity, refer to books by authors like Bipin Chandra, D.D. Basu, and G.C. Leong, respectively.

5. Read Newspapers and Magazines:
- Stay updated with current affairs by reading newspapers like The Hindu or Indian Express.
- Additionally, refer to magazines like Yojana and Kurukshetra for in-depth understanding of relevant topics.

6. Solve Previous Year Question Papers:
- Solve previous year question papers to understand the exam pattern, time management, and identify areas that require more focus.
- Analyze your performance and work on improving your weaker areas.

7. Take Mock Tests:
- Take regular mock tests to assess your preparation level and enhance your time management skills.
- Evaluate your performance and identify areas for improvement.

8. Revision and Notes:
- Regularly revise the topics you have studied to reinforce your knowledge.
- Make concise notes while studying, which will serve as a quick revision material during the last few days.

9. Stay Motivated and Healthy:
- UPSC preparation can be demanding, so ensure to take breaks, exercise, and maintain a healthy lifestyle.
- Stay motivated by setting small goals, rewarding yourself, and staying positive throughout the journey.

Remember, consistency and discipline are key while preparing for UPSC prelims. Follow this plan diligently, and you will be well-prepared to tackle the exam. Best of luck!