I got almost all A's and A*'s so I can help.
1)Research effective methods of revision
2)Make a plan that would work for yourself
3)Turn your phone off and revise whatever you goal is that day
Tip: Try to revise a short period of time everyday and don't revise 2 hours before sleeping as you need winding down time and good sleep. Remember, quality of revision counts not quantity. I only revised 2 hours each day from February (not including after school revision) and then I used my phone after the 2 hours. It's not hard.
You put your mind to it, try hard, revise, and you will do it. I wont tell you what my methods were, you can take a different route that works for you and arrive at the same place.
Just try your best. Don't be a perfectionist as that leads to mental disorders and unhappiness. There's more to life than your grades.