Dear Student ,

IFS(Indian Foreign Service ) is one of the toughest exams conducted by UPSC .

You may use these books for your IFS preparation :

• Indian Forestry A Breakthrough Approach to Forest Services (7th Edition)-- S. Prabhu K. Manikandan
• UPSC IFS Main Examination Guide: A complete book for Paper I and Paper II-- RPH Editorial Board
• UPSC IFS Botany Main Exam Guide Botany (Paper I & II) RPH Editorial Board--
• UPSC IFS Agriculture Main Exam Guide (Paper I & II) Main Exam Guide --Dr. B.B. Singh
• UPSC IFS exam Zoology main Exam Guide (Including Paper I & II) --RPH Editorial Board

Some preparation tips :

• Make a time table and use it regularly
• Clear the concepts in which topic you're weak
• Do revision
• Give mock tests on a daily basis
• Keep consistency
• Develop Time management skills

For your reference , you may go through this :

https://competition.careers360.com/articles/how-prepare-for-ifs

Hope this helps !