To score 620 marks in NEET, you need sheer dedication. You need to be disciplined and consistent with your efforts. You need to focus on NCERT and solving previous year papers. Solve as many NEET-based questions as possible. Study for at least 8-10hours daily. Focus on revision. NEET is accuracy and speed based exam. Try to not get too much negatives and increase your speed by solving questions while putting a timer.

To not feel too much sleepy while studying, drink water and take regular short breaks like use pomodoro technique, study for 50minutes then take a 100minutes break, repeat this cycle 4 times. After completing 4 cycles of 50-10minutes take a long break of about an hour. Don't use your phone during those breaks, take brisk walks, stretch your body or take power naps during the breaks.