I did AQA and got an A*, using a revision guide is really useful for learning content, I also used econ plus dal to help me learn the most difficult content and help me get higher level evaluation points, i also spent a lot of time learning the markshceme for the higher 25 and 15 mark questions, which helped me practice and mark my own 25/15 markers, this is really important as this is where the majority of the marks are, to get these high marks the basic content needs to be mastered especially for edexcel as im pretty sure you don't get to choose your questions like aqa do.