Hi. I have completed my 12th this year with 95.75%. I didn't write any entrance exams.So Can I study a year for JEE or NEET & other entrance

Yes you can.

I think you prefer to take coaching , as it will create the

1. Competitive environment
2. Keep on self motivating
3. Analysis your progress

In case of self study, these factors may not be completely gain.

What to do:-

1. Get or Purchase proper study material of all 3 subjects ( a book must contain theory as well problems) along with previous year papers.
2. Start with Basics and clear your Basics concept with the help of NCERT or other CBSE boards
3. Clarify your Doubts if any with help of faculties rather than books (as it bit time consuming)
4. Practice more and more, don’t read theory all the time.

You can refer various higher level books for each subject.

Physics - After solving NCERT you should go for HC Verma and Rassnick Halliday for Higher understanding of Subject,then you should attempt last year papers and Mock test.

Chemistry - For chemistry you should go for NCERT and only NCERT, for Question practice you can refer Other Books

• Numerical Chemistry by P.Bahadur or N Avasthi
• Organic Chemistry by M S Chouhan(Question Practice)
• Inorganic you should refer NCERT and NCERT Exampler.

Maths - After NCERT and NCERT Exampler and then you can refre book by Cengage Publications.

Go through it .It will help you