You need to be a graduate in any stream to pursue IAS. Once a graduate, then are are entrance exams that you need to prepare for
IAS Preparation Tip #1 – Work Smart Not Just Hard
IAS Preparation Tip #2 – Try Single-tasking it’s more efficient than Multi-tasking
IAS Preparation Tip #3 – Adopt the Just in Time Approach
IAS Preparation Tip #4 – Test Yourself Constantly
IAS Tip #5 – Make Micro Notes
IAS Preparation Tip #6 – Read Only What’s Absolutely Essential
No guide for IAS preparation can be complete unless you know important sources for finding information online.
These are some of the many resources for IAS exam:
Get all NCERT text books
check out IAS Kracker’s Online Test Series for IAS
First of all you need to be a graduate in any stream to pursue IAS. Once a graduate, then are are entrance exams that you need to prepare for. I am enclosing a link with more details.