Well I'm not a pro but I've been using my methods and achieving good results so just sharing.
1. Planning on what subjects you need to study on which day.
2. Find out your weakness in each subjects and work on it.
3. Do tonnes of exam papers.
4. Finding friends to teach you instead of teachers. ( I recommend this because a friend goes through the same thought process as you)
5. For Maths, practice. No other way around it.
6. Chemistry is to study and memorize. Same goes for all humanities subjects.
7. Memorizing formulas and do exercises to apply the formulas to know them better.
8. Languages. Books and newspapers normally work for me to get the best result of A1.
9. Divide your subjects such that you don't focus on doing the subject you like but focus more on the subjects you don't like.
Tips: Subjects you don't like, study in the morning when you're fresh. Subjects you are already good in, can be studied at night afternoon or evening.
Good luck for anyone taking examinations.