I almost forgotten I just recently wrote a bit on this topic-below is an extract from my senior study guide which you may find helpful. For the full guide which includes heaps of useful study tips, feel free to click on this link:
http://community.boredofstudies.org...w-excel-senior-year-studies-yr-11-12-a-5.html
REDUCING PROCRASTINATION
1)Set goals and stick with them-essentially this might be academic or related to extra-curriculars or your health, make sure you establish realistic short term, mid term and long term goals and stick with them until you achieve them. As a part of this you will need to make a sustainable study timetable/plan of some sort to manage your time efficiently and effectively.
2)Remove distractions-whether it be the compulsion to go on Facebook (perhaps try to log yourself out and remove the messenger app on your smartphone if you have one), removing your laptop from your sight if you don't need it, make sure that your table has only what you need and nothing what you don't need. If your study environment is noisy, perhaps try listening to some meditative/relaxing music or book a study room in a local library to study. Sometimes group studying can be an option as well-you might feel more motivated studying with friends.
3)Self-Discipline and Determination-this last point is perhaps the most important. At the end of the day, we all procrastinate, even I am guilty of the crime. However, you must try to develop a strong sense of self-discipline in making sure you achieve your HSC goals. This means that whenever you are conscious you are procrastinating, you stop the act and go back to study. There are three to four months worth of holidays at the end of the HSC waiting for you, you will have plenty of time to rest then. To earn the break without regrets you would/should have done better, the only way is to study as hard as you can while taking care of your body at the same time.