write lists of things you will have to have learnt in time for mocks/study leave
e.g. for maths your list might look like this:
-learn m1 formulae
-complete exercise 3C
-do past papers from 2006--2015
-etc
if youre having trouble focusing or doing homework/revision etc, set a timer on your phone to 8 minutes but you have to be INTENSELY focused and efficient for those 8 minutes and then repeat timer until you have completed something on your list
do not simply do the work school sets you, after each topic/lesson consolidate what you have learnt by writing notes and ALWAYS refer to the specification on the exam board websites so you dont miss out anything
always alwaysalways ask teachers for help. any lesson, any lunchtime, any free period
always go to school, people who have worse attendance have worse grades. dont mess around in your free periods and dont use them just to cram homework!!! you must use them for revision right from the beginning of the year
dont go out every day, limit yourself to 2 social events each week (MAX.) and you dont have to go out every single week anyway
but most importantly, learn to love the subjects you have taken and force yourself to feel excited and interested by them so you are encouraged to try your best and work more!
also important: you must take care of yourself, if you feel like you cant cope with stress or you are feeling down you must talk to someone and always leave time for yourself in the evenings where you can have a bath, eat very well, stay hydrated and sleep for around 8 hours a night!