Keep on flopping global politics A lvl exams

I love learning about global politics, but for some reason, when I write essays that I think are good, regardless of 30 markers or 12 markers, they don’t turn out to be good at all. Please someone who is doing EDEXCEL and global politics pleas help me out. It makes me so sad that I can’t just grasp the concept- I even have a global politics mock tomorrow and it’s my last mock.