Past papers! I find these work the best for "fact based" (if that's a thing) subjects, as opposed to interpretation/essay ones.
Just print off about 4/5 of them, do the ones you can, then fill in what you don't from the mark scheme. Go over it until you're confident that, if those questions came up for real, you'd be able to do most of/all of them.
Also make sure you understand WHY things are what they are. Then you won't just apply concepts like a machine, you will know exactly what you're doing and why. This, in my experience, means you don't have to bother "memorising" anything because (especially with regular practice) you will understand it enough that it easily sticks for ages, as opposed to dropping out of your head a few days after revising it.
Example:
Quadratic formula, it looks horrible at first sight! If you get why it works and how to derive it, then it's much easier to remember. If it comes to it and you forget it in the exam, then you can just derive it from ax^2+bx+c anyway.