Mr. Rajiv Srivastava in his blog post http://www.eblogs.in/rajiv-srivastava/how-to-get-in-iits
gave the following tips (I modified them slightly).
1. Select 60% of course in each subject and prepare them well.
2. Try to solve Olympiad problems.
3. Only follow one or two books in each subjects.
4. In examination you need to solve only 50% questions correctly.
5. Try to solve easy questions first.
6. For initial 5 minutes you go through complete paper, and select the questions which are comparatively easy.
7. Try to have strong fundamentals. Tricks and shortcuts always dont work, but still they can be helpful.
8. Solve previous year papers, for confidence but question will not be repeated in the examinations.
These suggestions are good. The first suggestion has to be interpreted that while you need to have a good understanding of every topic in the syllabus, develop a very good understanding of 60% of the portion at least.
Try past examination papers including olympiads to develop the confidence that you solve them in the JEE examination. Don't get frustrated after seeing the JEE paper. First identify easy questions and answer them. You may clear the JEE even if you can answer 50% correctly (based on past experience). So don't give up. You could answer past question paper. You can answer this question paper. Keep your confidence with you till the last minute. Stretch your brain coolly. You will answer the paper. Your effort will reward you.