for one thing, i realised then when people try to spend so much time memorising facts, they end up taking a longer time.
just try to understand the basics of the whole thing, and occasionally do practices. never cram for a test, it is useless. instead just try a short practice that you would do normally.
think of stoichiometry as maths: once u understand what addition is, everything comes to you naturally. you dont learnt addition by memorising equations