Hello

The best way to prepare for any exam is plan and work. Practice lots of sample papers and don't forget the last year's question paper too. They are a great resource.

You can go with the following Reference books:

1. Verban Reasoning by GK Puri
2. Concept of Health, Illness and Disease By Caroline Curre
3. Critical thinking by Larry Wright
4. Verbal and Non-verbal Reasoning P Prakash
5. The Age of Reason by Thomas Paine, Daniel Conway

Hope this  answer helps.

All the very best for your exams.