Well, I'll suggest you to prefer only cbse books because nothing come out of it in paper. Plus you can go for exam idea, it will help you. You can also go for 10 years where last 10 year paper of cbse is available.

While attempting cbse exam your presentation should be good because it will help you in scoring good marks.

Answers should be in point.

Try to make flow chart and diagram in exam, it will definitely help you to score good marks.

Do not write too much, write under word limits.

In starting of answer try to give brief introduction and in end of the answer try to give brief conclusion (by using Thus, hence, though etc)

I wish this will help you in your examination. Good luck!