I suggest reading (lots) of books. Before I buy one, I always tend to take a sneak inside and read the first 5 to 10 pages myself and you will easily notice whether you can cope with the level of English
According to me, books are one of the best ways to learn a language. They especially strengthen your feeling towards the language.
I'm reading Murphy's Revenge by Colin Bateman I like it a lot, I'm a hug fan of crime stories.