You can follow below tips -
Complete the NCERT (Physics, Chemistry and especially, Biology) books of 11and 12 standard, Solve previous year question papers.
Focus on important areas like-
**Physics**- Mechanics, Optics, Thermodynamics and Nuclear physics.
**Chemistry**- Mole concept, General organic chemistry, Periodic table, Chemical bonding, Coordination chemistry.
**Biology-** Ecology and environment, Genetics, Cell Biology, Morphology of plants and animals, Reproduction in plants and animals, Physiology of plants and animals,
Along with that try to solve as many mcqs for your practice and also solve complete mock test series.
Note : The syllabus of Medical entrances like NEET, AIIMS MBBS & JIPMER depends on NCERT. So it is advisable to go through the NCERT first and follow the above mentioned tips properly and you can also use standard reference books once you are done with all above said tips.
Good Luck!!!