I got straights A*s at GCSE and I've got to say I did not put in nearly enough work to get those grades, I have no idea how it happened, and honest to god this is not me being modest. I now say my secret is eating a banana before each exam, it's the only plausible explanation. In truth, bananas are awesome brain foods.
But, for my revision method I prepare mindmaps in advance then in the days leading up to the exam I walk around my room reciting the mindmaps out loud to myself. This means I have the mental picture in my head of the mindmap (I don't have a photographic memory but I do remember in pictures more than anything else), the walking around my room gets oxygen to brain and saying it out loud consolidates it all.
However, we'll see this summer whether or not my GCSEs were a fluke!