It will be better if you refer the government sanctioned textbooks for boards because it covers all the points needed for an answer which are needed to get full marks in your answers. Your answers and their presentation must be very good if you aim for scoring more marks in the boards. Chemistry should include all the reactions, intermediate steps, etc. Physics should have theorems properly derived and maths should include all the formulas along with answers. At the same time, make sure you know  almost everything so that no question gets out of your comfort zone.

Best wishes. Thank you.