Hi there.

Just keep solving questions until your concept becomes crystal clear and you develop a problem-solving approach. Just for the sake of your question, it is advisable to do 250+ different types of questions from each chapter. Cracking the NEET examination comes at the cost of hard work, patience, determination, continued practice, and a lot of focus on proper time management.

The following books might prove helpful in your preparation.

First of all, for all subjects i.e Physics, Chemistry, Biology study the NCERT books cover to cover at least twice. For Biology read NCERT as many times as possible. For only the text material of Biology, you actually don't need to refer to any other book. NCERT is more than enough for biology. You might doubt this but trust me NCERT is really really enough for Biology. I can't stress more on this FACT.

For Physics, after completing NCERT complete all examples and questions from DC Pandey Objective book of physics by Arihant publishers. Revise the material as much as possible.

For Chemistry, after completing NCERT, for physical chemistry do MCQ type questions from Vibrant Academy's book of Narendra Awasthi. It is a book for JEE but for NEET you only need to do and complete the TYPE 1 questions from that book and that will be enough. You will find direct questions in NEET from this book.

For inorganic chemistry, NCERT is enough. Read it as many times as possible. The same studying principle of Biology applies to Inorganic Chemistry as well.

For organic chemistry, solve Vibrant Academy's book by MS Chouhan. This book is specifically for NEET and will be enough to score high in the organic chemistry section.

For Biology, along with NCERT solve all questions from the book of MTG NCERT at your fingertips. Solve this book and revise it as many times as possible. You will end up getting more than 300 in Biology if you have an excellent hold of NCERTs in biology and if you complete the aforementioned book.

LASTLY, your preparation would be incomplete if you don't solve previous years questions. For that refer to MTG chapter wise previous year question for all subjects i.e. Physics, Chemistry, and Biology.

All these books are easily available in the market and online.

Hello Sanchita,
NEET is the National level entrance exam for admission to Medical, Dental and AYUSH courses in the country. NEET 2019 exam will be conducted by National Testing Agency and the exam will be held on May 5, 2019.
To start your preparation, you should know the detailed syllabus and exam pattern. See, Clearing of basic concepts is essential to score well in the exam. You should focus on clearing the concepts. NCERTs are the best books for basics and you should refer to other important books for in depth knowledge of the topics.

Except AIIMS MBBS and JIPMER, NEET UG is the only entrance exam for admission to  medical colleges and competition is also high so you need to manage your preparation smartly. Make a time table for your studies and follow it religiously. Make short study notes.
Solving previous year question papers will also help you to know about the type of questions asked in the exam and for practice.
You can go through the link below to check the detailed preparation tips, syllabus, important topics, important books-

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

Good Luck!