How to get good grades:
1. On weekends, go to a tutor for 5 hours
2. On weekdays, ask your parents for worksheets on any subject
3. If you have any break (Summer break, March break, etc.), use it all on school work and such
4. The week before a test, study until 1 in the morning
5. Repeat for 5 years
This worked for me and it should work for you.