To start the preparation from the scratch, first complete your NCERT, try to focus more on important topics only simultaneously keep doing sample papers and previous year papers. Along with that you can follow standard books like -
Best Biology Books for AIPMT/NEET Preparation:
NCERT Biology of Class XI and XII
Trueman's Biology Vol 1 and 2
Objective Biology by Dinesh
Pradeep Publication's Biology
GRB Bathla's Publication's for Biology

Best Physics Books for AIPMT/NEET Preparation:
Concepts of Physicsby H. C. Verma
NCERT- Physics Part 1 and Part 2
D C Pandey Objective Physics
Fundamentals of Physicsby Halliday, Resnick and Walker
Problems in General Physicsby I. E. Irodov

Best Chemistry Books for AIPMT/NEET Preparation:
NCERT Chemistry
Physical Chemistryby O.P. Tandon
Organic Chemistryby Morrison and Boydfor Organic Chemistry
Moderns ABC of Chemistry for class 11th and 12th
Concise Inorganic Chemistryby J. D. Leefor Inorganic Chemistry
Dinesh Chemistry

Note :- As there are many books available in the market, it is advisable to follow standard books only and choose the books which make are easy to understand and clear all your doubts.

Good Luck!!!