If u want only 90-100 then don't study d whole syllabus..just pick up imp chapters
1.modern physics
2.gravitation
3.rotational motion
4.fluid mechanics
5.optics
6.current electricity

If you are preparing for NEET/JEE, focus on them. Spend only last 1.5 months for boards.
To get 90+, ensure that you get at least 28/30 in practicals. Comprehensive practical manual is a good one.

For theory, focus on derivations. Solve NCERT exercises. Read NCERT text at least once, and optics and semiconductors at least twice.

Solve past year papers. U like papers are very good.
Best of luck for your exams.

For board exam just focus on ncert Infact major portion of the paper is covered by derivations numerical constitute very less marks ...
Just do ncert within chapter questions and exercise ( if u want ) exercise is not necessary ...
And practice derivations

Just do each and every derivation of each chapter. Since the numericals are 13 numbers only..