How to score marks in maths in G>C>E o'ls

You need to know all your lessons, and then you practice, practice and practice again. If you have good answer sheets, then compare your answers with those of the sheet when you complete each problem you are practising, NOT while you're doing the problem. When you think you get everything, do a sample question paper, there are many available. Work at your ease, and correct the paper yourself using the answer sheet AFTER you did it all.

When you feel confident, do some more full papers under time pressure and see what you can do, and still mark yourself after completing the paper :)

Just go through past papers.do them and find the mistakes and do them again!