Thanks for posing the query. Time management is important skill. Can you please provide your current education?
To guide you properly, I need to know your present education, interest, subjects,and your routine.

However, in general, following guideline may help you a bit:

Assess your interest: Asses which subject you like the most and easy to grasp, which subject is very interesting but difficult to grasp, which subjects you hate the most, difficult to grasp.
Develop realistic time-table: Now based on the difficult level, you need to contribute time and efforts.
Put first thing first: Prioritize the subject that requires immediate attention. Everyday focus on one or two subjects apart from regular home work.
Follow your time-table strictly: You need to be strict. If you follow your time-table, reward yourself by going for a walk, eat cadburry or watch a movie.
Audit your day's study:Before you sleep, recall what you have done whole day. What have you studied, what have you remembered so far. WHat is the plan for the next day.

Hope this helps.
With Best Regards,
Apurva

Managing timetable requires discipline and with coaching, school and extra curricular it might get hectic. Suggest you to sit down with some counselor/ Seniors/ Teachers/ Parents to help you see where is that you need help with time management.

Cutting down few minutes of sleep and TV does help.