Preparing for the geography optional in UPSC requires a strategic approach, especially for students with an engineering or science background. Here are some effective strategies to excel in this subject:

1. Understand the Syllabus:
- Begin by thoroughly understanding the syllabus of the geography optional subject. Analyze the topics and subtopics mentioned to have a clear idea of what needs to be covered.

2. Refer to Standard Books:
- Start by referring to standard textbooks recommended for geography optional. Some popular books include 'Physical Geography' by Savindra Singh, 'Human Geography' by Majid Hussain, 'Models in Geography' by Majid Husain, and 'India: A Comprehensive Geography' by D.R. Khullar.

3. Analyze Previous Year Question Papers:
- Analyzing previous year question papers will give you a good understanding of the type of questions asked, the weightage given to different topics, and the overall pattern of the exam. This will help you focus on important areas and allocate your time accordingly.

4. Make Detailed Notes:
- While studying, make detailed notes of important concepts, definitions, diagrams, and examples. This will help in quick revision during the last few days before the exam.

5. Utilize Online Resources:
- Explore online resources such as EduRev, which provides a wide range of study materials, notes, and question banks specifically designed for UPSC geography optional. These resources can supplement your preparation and provide additional practice.

6. Solve Previous Year Question Papers:
- Solve previous year question papers and sample papers to get a feel of the actual exam. This will help you understand the time management required and improve your answering skills.

7. Join Test Series:
- Enroll in a good test series for geography optional. This will not only provide you with regular practice but also help you assess your performance and identify areas that need improvement.

8. Develop Map Reading Skills:
- Geography optional requires good map reading skills. Practice locating and marking important geographical features on maps. This will help you in answering map-based questions accurately.

9. Analyze Current Affairs:
- Geography is a dynamic subject, and it is important to stay updated with current affairs related to geographical phenomena, environmental issues, and international developments. Regularly read newspapers, magazines, and online sources to stay informed.

10. Time Management:
- Allocate time for each topic based on its weightage in the syllabus. Create a study schedule that ensures comprehensive coverage of all topics while leaving ample time for revision.

By following these strategies, engineering or science background students can effectively prepare for geography optional in UPSC and increase their chances of scoring well in the exam. Remember to stay consistent, dedicated, and disciplined throughout the preparation journey.