Hi,
It is unclear as to which entrance exam you are referring to here but, I can suggest you for the NIFT exam. Also, the strategy remains the same for any other exam as well.
The first and foremost important thing that you must remember: NIFT examinations are conducted in the month of January and the Boards exams in the month of March. If you prepare for NIFT throughout the year, you need not worry at all. The exam is quite easy to crack and requires very little effort if you are good at mathematics and have some sketching skills.
If are currently in the 12th and would be taking the 12th boards in the year 2021, I would recommend joining a weekend class at any coaching near you. The coaching will help you be in discipline and also boost your preparation. Pahal Design has centers all across India in various cities and over 35 centers.