How can I prepare for jee mains cause for me I have got classes during Saturdays and I come back school only at 5:30 in evening

Look for jee main you don't need to work very hard you just need to be regular from this tough schedule  I think you can manage atleast 2-3 hrs daily that is more than sufficient jst spend that time for problem solving and enhancing your basic concepts

Hello Ostin,
First of all, you should have the concentration power after that you can follow your timetable easily. Also keep in mind while you are making your timetable that it should not be hard to follow it. In starting, your timetable should be easy to follow, then gradually you can increase your study hours with concentration also. To study smartly, you should follow a proper routine of studing new chapters, solving numericals,and revision also in all three subjects. All three things should be the part of your preparation strategy in daily routine.
Your time table depends upon you and your situation like sleeping time, time for other home works or the time in which you are more comfortable for study i.e. quality time for you (in morning, in evening or in night). So, you should make your time table in your own way.
The main thing is that you have to build your concentration level, then only you can stay focused on your goal. I would like to say that please limit the study time between 10 to 12 or 13 hours (school+coaching+self-study) and please increase your concentration and speed of reading, understanding and solving the problems then you will not face any kind of difficulty.
For preparation of exam, the most important thing is your confidence after that you should know the whole syllabus and make your plan properly for learning new chapters, solving the numericals and revision. All three things should be the part of your preparation strategy in daily routine.
Your basics in Physics, Chemistry & Mathematics should be very clear upto 12th std. You should read the NCERT books for basics. Then HC Verma for Physics, RD Sharma for Mathematics, OP Tendon for Physical & Inorganic Chemistry, and Organic Chemistry of "Arihant Publication" for detail or extra knowledge.
You should also try to solve the previous years question papers, this helps too much and you should also give the mock test to rectify yourself and build your confidence level.
For more preparation tips, importants topics & books, you can go through the link given below
Https://engineering.careers360.com/articles/jee-main-2019
In this way, you can prepare well for the JEE Main and the JEE Advanced.
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All the best for your examination.

Syllabus for JEE Main is basically Your class12th Syllabus So Even When You are in the class You are Preparing for it in Some ways, What You need to do is make a Proper Timetable that what You can read in the class and what You need to do for self study once it is clear You will be able To utilise TYourclasses as well for You Preparation of JEE Main.