Hello Yash

For scoring in boards you should do the foremost thing i.e. practice writing the answers.  Since you didn't mentioned your subjects in question so I'll tell you overall , for science subjects as well as commerce and arts NCERTs are the best,  do the exercise questions given which most of the students used to skip. 

Revise and revise complete your syllabus till November, then only you'll get much time for practicing last years boards question papers. 

Hope it helped you

Good luck