NCERT books are very important for your NEET preparation as syllabus is based on them. 

It helps you to make your concepts strong. 

NCERT is very important for biology as you can get direct questions from NCERT book. Exercises which are given at the end of the topics are very important.

You can also solve NCERT exemplar as well.

Solving previous year papers are also important to understand the type and level of the questions.

It is important that you should focus on the topics which carries more weighatge in the exam and solve as many as MCQs for your practice.

Good Luck!!