Hello there,
You should divide your time equally for classes, self study and rest. Remember, you should rest your body and mind too, to ensure your brain work properly and efficiently. Make a timetable for yourself do that your day doens't seem hectic and tiresome. You should do self study everyday to make sure you complete your syllabus beforehand and keep enough time for revision. Take rest for an hour after your regular classes then sit for self study with full concentration.
Hope this information helps you.
Good luck!!