I agree on the importance of reading, too.
Even passive reading helps a lot. For instance, it helps develop sort of '
feeling' for collocations, which is very useful when tackling both the "open cloze" and the "selective cloze" exercises in Paper 3 (English in Use). Passing these exams it's not simply a matter of studying and memorizing grammar, verb patterns, prepositions and collocations ... it's first and foremost a matter of '
absorbing' the language.
(Just my humble opinion

)