• Follow standard books, and get past year papers with a decent question bank. If you are in a coaching institute, solve their material. All of them are nearly the same.
• Focus on the quality, rather than the quantity. Even if you solve 10000 questions, there will be a question that is new to you.
• Always use a timer during your problem-solving sessions. This will help you build a comfort level with timed tests. You will learn to manage your time better.
• NCERTs are really really important! Supplement your studies with the exemplar problems. You can find all types of problems here. Single Choice, Multiple Correct, Match the following, Assertion-Reason etc. 
• In your first attempt, mark the important sections and problems you weren’t able to solve. When you revise, attempt these first. Refer the theory only if you need it. Make your own notes. This helps to recall things easier.
• Have a monthly and weekly breakdown of the topics you want to cover. Try to follow this schedule. Stay ahead if you can. Without planning, lot of time is wasted on short chapters, and the lengthy ones are rushed. This leaves gaps in preparation. We do not want that. Do we?
• Often times, students avoid guessing. If they are aiming for 200, they attempt questions worth 200 marks. The obvious result is that they end up getting fewer marks. Attempt at least 70-80% of the paper. This is very important. Do intelligent guessing by eliminating options if you need to. Remember, if you want to score high, you need to attempt more
• Okay, you may use your own judgment here. Based on past trends, Chemistry paper is the easiest and can be solved in about 30-40 minutes. You can use the saved time in solving the Physics and Maths section. Solving more questions at the start of the examination will also boost your confidence.
• The cooler your head is, the better you will perform. Often times we see a problem we have solved before, and quickly tick the answer. Only to find out we checked the wrong option. Even if you have seen the question before, avoid blind ticking. Solve it till the point you are sure of your choice. Plan well and you will have enough time.

Eat healthy, stay healthy. You will study better and score more.

 Hope you find it helpful

Good luck!

Hello,

With your question, it seems like you are aiming for JEE Mains 2020. Well, there is plenty of time till JEE Mains 2020. You should be well prepared for that by utilising the time you have got. 

I would say you should begin your basics with NCERT books. For Physics, solve questions from HC Verma for class 11th and Class 12th also. If you to solve more number of questions, you should solve D.C. Pandey's book too. Derive the important formulas on your own for a better understanding of concepts.

For Chemistry, read the NCERT books thoroughly. Solve questions from NCERT exercises. Remember all the Physical Chemistry formulas and understand the mechanisms for Organic chemistry. For Inorganic chemistry of JEE Mains, NCERT textbook is enough.

For Maths, solve as many questios you can by understanding the concepts. Also, solve the previous year questions of each subject.

All the best!