To start with your preparation for NEET exam you should refer NCERT books it will help you to build your base strong and you can clear your concepts.

Apart, from NCERT books you can refer OP Tandon and J.D Lee.

Make sure you go through previous year questions to understand the level of the questions and focus on the topics which carries more weighatge in the exam you can also solve as many as MCQs as well for your practice.

Good Luck!!