Dear mam I'm preparing for bitsat could you please give me some ideas or trick to study which helps me to score good

Yeah sure. I hope you are very well aware about the pattern and syllabus of bitsat.
So for the sections like Physics, Chemistry, Maths and Bio you need to strengthen your 11th and 12th basics and concepts. And for English vocabulary, Grammar, reading comprehension and composition and for  Reasoning verbal and non- verbal reasoning. For reasoning you can use R.S AGRAWAL reasoning book or M.K Pandey reasoning book.
Also , do some sample papers, as it will give an idea of paper and will help you in setting up your mind.
For Grammar you can use High School English Grammar and Composition book by Wren & Martin book. It is a very good book.

Also, I am here Sharing you the page of our site which will also helps you in topics for physics, chemistry, maths and bio. Also it will help you in decoding your areas.

Link:
https://engineering.careers360.com/articles/bitsat-exam-pattern/amp

I hope this helps you.

All the best !!