How can I crack iit jee in 12 months without coaching?

Maintaining a proper schedule for every task that you do can lead you to success.Prepare the best way by appearing as many mock tests you can, and analyze the results regularly. Try solving the portion which you find difficult in the mock tests and create a strong base. Make separate sheets for formulas and theorem that can help you a lot while solving numerical in Physics and Mathematics.
Make sure you revise every topic thoroughly and prepare well every topic by revising time and again. Also prepare separate revision plan for last minute preparation.