If this is for NEET, For Physics, Try to learn the formulas and derivations, so that you can solve problems in one go.  A smart, thorough approach towards Physics section can significantly boost your rank. Chemistry is a tedious subject and requires a lot of visualization which makes it difficult to comprehend for some. Chemistry is divided into Inorganic, Physical and Organic chemistry. For inorganic chemistry, you must refer to the NCERT. Organic comprises of many reactions and reagents which can be practised by writing over and over again.  Physical chemistry requires a comparatively deeper understanding of concepts, so preparing with the NCERT and referring to study material a level higher than NCERT should be the way to go.