Please tell me fast .

Dear Sarita , 

The only way to score good is study hard with dedication.. 

For IIT JEE preparation .. the first very important thing is clear and enhance your concepts .. jus keep this thing in mind that building concepts and practicing a lot is damn important for IIT preparation..
Always start from BASICS because "without base, there will be no altitude…  Never prefer solutions of questions before doing SELF-ATTEMPT at least five times till you get the right answer because "without fall you can not stand at once". 

Study without loosing the concentration coz studying 2 hours with very good concentration is equals to studying 5-12 hours without any concentration. .  and  have a confidence in yourself.   

All the best !!