IIT Preparation

Before preparing for IIT decide, you really want to be an IITian or you just want to get admission in IIT because of the good package, parents, society, etc. If it is the second reason then don't prepare for IIT. Do what you really want to do. Now, if you really want to be an IITian and you like engineering. Let's start. Forget whether you are weak, average, good or brilliant student in class 10th. It does not matter. Start preparing for JEE Mains right after 23 days of 10th board examination. Coaching, School, and Self-study. After class 10th, you have to choose whether you will join a coaching institute, go for an online coaching or do self-study. And if you want a decent rank, choose a coaching with dummy school or traditional schools with self-study. If you really want to crack JEE with a decent rank, don't go for both, traditional schools and coaching. It would be very difficult as you will be left with very less time I. e. not sufficient to crack JEE with a decent Rank. A lot of time is required for self-study and for JEE preparation, self-study is must. My opinion. I think you should go for online Etoos coaching for Physics and Chemistry (very cheap as compared to the traditional coaching and Etoos has good faculty members) and for maths, you should go for Mohit Tyagi's YouTube videos (all lectures are available for free). No coaching can compete with Mohit Tyagi sir. Important books for JEE:
After that, you need good books (complete one, then choose other). For Physics:
NCERT (must). HC Verma (must). DC Pandey (after you complete the above books). I. E. Irodov (optional or don't try to solve this above mentioned (it's a warning). For Chemistry:
NCERT is must and most important. For Physical Chemistry, GRB-OP Tandon. For inOrganic Chemistry, JD Lee. For Organic, NCERT is sufficient. For Maths:
Choose any one publication (Arihant, Engage, TMH, etc.). Book Series
Maths NCERT is not that important, but you should do miscellaneous exercises from it. Summary:
You should study constantly for 8-14 hours for a decent rank. Studies are most important. You should make clean and clear notes that will be very helpful during the revision time. You should revise after 3-4 weeks. Test Series:
If you did not join any coaching, a good test series is must. Some of are:
Resonance
Allen
Fiitjee
Bansal
Toppr
If You will follow all above and do hard and smart work, you will surely get admission in an IIT.

I will suggest you to first strengthen your fundamentals as it is very important for your class 11th and 12th board and very well needed for the IIT exam. IIT exam is not a rocket science, you just need to be more dedicated to proper time management as you have to balance your 11th with IIT preparations.
For example, if you read Kinematics, I will suggest you to make your fundamentals strong with a standard book or any other means with which you feel comfortable then solve your class 11th questions first and analyze yourself and then refer to the previous year question papers of IIT and try to solve them as well and analyze your solving skills and time management.Just remember, to achieve something different, you have to do things little different.
I hope that this will help you to decide what to do, and if you have any doubt, feel free to ask.
All the very best for your future!