Gcse A* in Mathematics Watch
Like the others have said... Practice practice practice! Corbett maths is amazing... I've been doing the 5 a day since September and it really does help with keeping all the topics fresh in your mind... Make sure you understand how to do everything and focus on A* level questions (I can send you a list if you like)
Feel free to PM me with any topics you're struggling with and I can go through them with you - I'm on an A* and with all the effort I've put in I'd be devastated if I didn't get this at the end of the year... Good luck! Hope you can move up!