Hi, to score good marks at first you need to know the complete NCERT Syllabus. Knowing the syllabus will make you aware of the important topics or chapters to cover for the exam. Science is a subject which needs regular study as it contains formulae and theorem-based questions which are asked from the Physics portion. So, one has to study well to learn all the formulae and theorems by heart. Use the right NCERT books class 10 Science for preparation as these books are useful not only for academic purpose but only for various competitive exams such as for engineering JEE, and medical exams AIIMS, NEET etc. 

Hi Ganavi,

You might be having all the three streams that are physics, chemistry and biology in your science paper so you have to practice all the three subjects very well from the sample papers and their practice papers as well. Try practising the sample papers provided by CBSE. Provide utmost importance to all the diagrams and chemical equations along with their valencies and atomic numbers.