IIT-JEE preparation requires a lot of energy, that should be focussed in right direction. For correct guidance, a proper mentor is required. I suggest to choose a proper mentor and learn to keep faith in your teachers.
Also learn when to compare yourself with others and when not to do so. Also keep in mind that your hardship is going to be very fruitful. When you feel low, get help from your mentors. All my classmates tell me that they as well as I felt low while IIT-JEE preparation. Always remembner tough times never last, but tough people do.I had to work hard for getting a good mentor, at that time nothing like this portal existed where one can come and discuss his problems freely.
Always Remember:
Tough times never last but tough people do….because they know that it may be impossible with man, but with GOD nothing is impossible.
Best of Luck.