1) Approach Revision and study periods just as athletes approach training. Train deliberately, stop shying away at what topic you're usually bad at. Identify your mistakes and face them head on or you'll never improve.
2) Remove distractions and focus, Turn off your phone, disable your internet, discipline yourself and get stuck in.
3) Get inspiration and get to work. It's important to discover what you're working towards, but more importantly, its crucial to pan out what it takes to get there. Create a map to meeting your goal( be it a certain number of A*s or a university place) write out what it takes to get there, and start
4) Keep yourself accountable, write out what you aimed to have gotten done at the end of the day in the morning, in the evening review what you have done and if you've fallen short, critique yourself and address where you've fallen short. This is a lot easier when a friend or family member is holding you to your word.
5) Time your exam practice. In my opinion the most important, you've got to learn to think fast in the exam, even if you covered the scheme three times over it won't count for anything if you don't finish the paper in time. Practice your exam papers in exam conditions
EDIT: typo