I am so happy to see your interest toward IIT, from 10 class itself. First of all brought a foundation study material from any of the reputiated coaching institutes online or offline. Then start working out on them along with your class 10 syllabus. If you face any problem on any topic, clear it right at that instant. Be more focussed on application part of the concepts in numericals and practical problems. For any help you can also go through online to discuss concepts and their applications.