Hello Aspirant

Don't pressurised yourself for marks, I can understand the importance of class 12 marks but don't be in pressure.

Try to be relax and study.

If we talk about the preparations, CBSE set exam from the NCERT syllabus books.

If you do NCERT books religiously then it'll be great and increase your chances of scoring good.

Your first step is to cover up the whole NCERT Book and if you left with time than you can pick up any sample papers for class 12 and also previous years exams are very important to do.

Try to make a timetable for yourself and set weekly targets and divide the syllabus into topics, it'll make it look easier to cover-up fast and also it'll keep you motivated for the results.

Also think about positive results which you will live after scoring 95%+.

Hope this information is helpful.

All the best for your future.