Hi there

That's a very good question, I must say. The most important advice is stop thinking about such things and start studying right away. You must have received an answer for your question from the statement mentioned above. The most important qualities are being hard working, focused, determined, motiavted enough and having the zeal to perform better even after consecutive failures.

Those qualities are not enough unless you don't make any effort to study hard and to prepare high end in order to really crack the exam. Again, focus on studying, only having such qualities won't matter if you don't work towards your goal.

To give you an idea of books required for cracking the exam, 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.

No one can stop you from cracking NEET if you diligently follow and solve these books as many times as possible.

Wishing you luck!

You should be good among all the three subjects Physics, Chemistry, and Biology but Biology should be best as its scoring and its Backbone. Focus on NCERT while preparing for Chemistry and Physics as Physics will be a little bit easier compared to One for Engineering Aspirants so If you are able to solve basic Problems in Physics You are good Going. Biology should be learned Line by the line from NCERT and similar for Chemistry.