Short answer: Read NCERT line by line first, then add one practice source per subject. Biology in particular depends heavily on NCERT language and diagrams.
Biology comes first
Read the Class 11 and 12 NCERT biology books line by line, including figures and tables, and revise them more than once. Most students find that careful NCERT reading gives the best return for the effort.
Physics and chemistry
Use NCERT to build concepts, then solve questions from one good practice book per subject. For chemistry, keep short notes on reactions and exceptions that you can revise the day before an exam.
Adding practice books
Add a question bank only after you have read the chapter. Use chapter-wise tests to find weak areas and return to NCERT to repair them.
Buying smart
NCERT books are inexpensive and widely available, so buy a clean set you can annotate. Practice books of the same edition can often be bought second hand to bring the total cost down.
Related: turn old NEET books into cash.
Frequently asked questions
Is NCERT enough for NEET?
NCERT forms the core of the syllabus, but most students add practice questions from one extra source per subject.
How many times should I revise NCERT biology?
Revise it several times before the exam, and use diagrams and tables as quick-revision material.
Can I save money on NEET books?
Yes. Practice books of the correct edition are commonly bought second hand, and you can sell yours when you finish.