Reading is another way to absorb information, reading is more formal than spoken language. Which is why you need a higher level of understanding of the language with written words, phrases and idioms. The easiest way to remember these is to set up a collection note book and keep the words in different categories, for example, adjectives, adverbs, verbs, nouns and so on. Keep topping up your collection with new higher level words every few days, finally you will have created your own useful word collection.
Once you have started reading, try newspapers and magazines. You will find them quite useful and easier to understand. The words and idioms in newspapers and magazines are more informal than oral language, but not as hard as they would be in a novel, just right for beginners. So try to read as much from a newspaper and magazine anytime and anywhere.
Keep doing that for a while, before you start reading novels.
Remember you don’t need to look up every single new word in the dictionary, this will only put you off continuing to read, just keep reading to try to get the overall picture. Try to guess the meaning by context, and you can underline the words you don’t understand. When you finish reading a section, then it is the best time to look them up in a dictionary to get the correct meaning. Meanwhile, add them to your word collection.