1. The first thing people do is not understand the magnitude and seriousness of this exam. This exam is very important turning point in life. Some are also overconfident. They think that the exam is easy.
2. Reading unnecessary stuff. Reading all guide books and other books but not reading NCERT.
3. Skipping classes. People skip coaching class lectures and roam around and expect ranks. Sometimes you need to sacrifice somethings to achieve something.
4. Not giving tests. Fearing tests. Tests are good for improvement of performance.
5. Not taking a break from social media. Social media is the biggest reason for not getting selection. Its necessary to stay away from it.
6. No strategy. Studying whatever they want at anytime. You need to have a proper schedule and timetable to study and plan everything.