HI
By seeing your performance Its obvious that you have got a potential in you. But the main reason for low performance among scholars is Stress . Recently an IITian who is now the Dean of a college said me that Its stress that makes us perform less than what we are capable of. Some tips he gave were :
1) Have nice sleep everyday , Have nutritious food and stay healthy.
2) Study regularly and systematically ( This is very IMportant ! ) and cover your portion in time.
3)Understand the topics as you learn.
4) Enjoy your studies and try to find applications of what you have learnt.
5) Sleep early before the day of your exam.( You get sleep only if you have studied well )
6) Assess your capacity , And set realistic targets.
7) Have cool mind and dont discuss anything with your friends on the day of your exam ( This does maximum damage if you discuss problems before exam)
So prepare well , Enjoy ur learning and you will be out with flying colours in JEE 2008. Good luck.
Cheers!