You should start your preparation by NCERT books to work on your basics and to make your fundamentals strong.

You can refer below recommended books for your preparation

Physics - For Physics you can go for HC Verma, Resnick Halliday and Irodov

Chemistry- You can go for O.P Tandon

Mathematics - You can go for R.D Sharma, Arihant and S.L Loney.

Make sure you refer previous year papers to undrstand the exam pattern and level of questions. Solve as many as mock test series to analyze your preparation level at regular interval of time.

All the Best for your Preparation!!