The following units from Physics will be covered in JEE Main:
Optics, Dual nature of matter and radiation, Electrostatics, Thermodynamics, Laws of motion, Communication systems, Electromagnetic induction and alternating currents, Electromagnetic waves, Physics and measurement, Kinematics, Oscillations and waves, Atoms and nuclei, Current electricity, Magnetic effects of current and magnetism, Properties of solids and liquids, Electronic devices, Kinetic theory of gases, Work, energy and power, Rotational motion, Gravitation.
Here are some tips:
1. Touch every topic.
2. Find out your weak areas as well as the topics that you find easy.
3. Divide your time and initially, be thorough with the topics you find easy. Make it a point to leave enough time to work on your weak areas.
4. While working on the weak areas, make sure you understand what you are studying. If you don't understand at one go, go through it again and refer to other sources apart from the textbook. A little discussion with friends might help too.
5. Take notes. Reading the entire text all over again is not very much time saving.
6. Revise. Revision is always the key.
7. Make it a point to practise sample papers and previous years' question papers regularly. They help you understand the exam pattern better and give you an idea of the topics that should be given more priority to. However it is always a better idea to cover the entire syllabus. It is just a matter of organising your time well.
All the best!