Lack of disciplined routine
For every exam, there is a proper set of discipline which is completely based on your pace and way of studying. If you do not make a proper schedule about the syllabus and stick to it, there is a big chance that you will not be able to succeed.
Distractions
While preparing for JEE you will come across a number of distractions like friends, family functions, weddings, birthday parties, movies of your favorite stars, etc. You have to get rid of all these distractions and concentrate on your studies.
Understanding of exam pattern
A lot of students miss to check the pattern of the question paper while preparing for the exam. In such cases, the students are not able to complete the exam in time. It is important to check the syllabus and the pattern. You have to prepare accordingly.
No mentor
Mentor can be a teacher or a senior student who can guide you towards success. While all coaching centers will provide you the study material, the only mentor can guide you on how to use it. Find one for yourself and make sure you follow the path suggested.
Personal factors
Lack of good health, sleep, nutritious food, exercise and mental stability for the examination can result in failure. You have to address these areas as well.
By keeping a few points in mind, you can easily avoid failure in the JEE.