Hello, to clear any competitive exam first important thing is to be aware of the syllabus as you have to know what topics are to be studied and which topics are important and carry more marks. Then divide your study time according to the distribution of marks. Al,so practice as many previous years question papers to know the type of questions asked in the actual exam. Use the best books for reference for subjects like Physics, Chemistry, and Biology along with the NCERT textbooks. Go through this link I have shared below to know each and everything on how to prepare for NEET UG exam -

https://medicine.careers360.com/articles/neet-2019

All the best for your preparation!