What are the ways to prepare for IIT after 10th class?

You have got plenty of time to prepare, if you are planning to achieve the glorious victory.

A few step that you can take immediately after tenth before results are announced

1. Join any tution classes in your own city.
2. Buy books.
3. Early bird catches the fly. Try to complete eleventh board topics before every one else in your batch does.
4. Start doing objective questions, Use books like Pradeeps to get questions.
5. Read some mathematics books which gives you real understanding of the topics you have studied upto tenth.
6. Read every topic of maths and physics upto what you have studied in one go, and jump directly to the units and measurements chapter of class 11th physics. (SL Arora Simplified Physics for theories and board level questions)
7. Get to know some seniors whohave really cracked JEE adv.
8. Avoid reading success stories online about jee, rather read some about the failures.
9. Plan to work smart, not to work hard.
10. Befriends like minded students.

Befriending like minded students will create a healthy competition in your own peer circle, which will eventually give you a boost.

After your tenth results are out, consider joining a reputed coaching institute when your home city doesn't have a good coaching centre. If your home city has one avoid the thoughts like 'Do I need to join Kota/Hyderabad/Delhi?' etc.

Wherever you study, what really matters is what you are doing, what you have done and what will you do. If you are keep searching about reputed institutions, you will really waste your time. Be bold with your decisions and be ready to face the stress of entrances like a viking.