You need to increase your vocabulary. You need to build your lexicon. You need to learn more idiomatic expressions. Does this mean studying vocabulary lists? No. Does that mean buying books that list idiomatic expressions in English and their meanings? That may or may not be helpful. Does it mean going to the Internet and studying idiomatic expressions that are listed at websites? Perhaps, but that wouldn’t be all. Does it mean learning the word of the day that is given by online dictionaries? No! You need to build a personal lexicon. You need to maintain a lexical notebook. You need to learn words and expressions that are interesting to you and will be useful to you. You need to learn words and expressions that are part of your environment. Where can you find these words and expressions? You can find them by listening to the radio, by listening to those that you speak with on a daily basis, and by even listening to those that you don’t speak with. You don’t have to converse with someone in order to listen to someone. Of course, you can find new words and expressions by choosing challenging reading material that is interesting to you: newspaper and magazine articles, books, short stories. In order to start building your new lexicon, I suggest starting by finding something to read.
Now that you have chosen something interesting to read, here is what you need to do. You need to write down the words and expressions that you don’t understand. Take note of the page number and paragraph that the words or expressions are on as you read. After you are done reading, go back to the words and expressions that you didn’t understand and write them in your lexical notebook. Leave space to write an explanation or a definition. From the context, see if you can figure out what the words or expressions mean. After you have done this, go to a dictionary. For idiomatic expressions and phrasal verbs that you are unfamiliar with, I strongly recommend taking advantage of Cambridge Dictionaries Online. It is important that you practice these new words and expressions by writing your own sentences. This is helpful in incorporating them into your daily conversations and speaking habits. Don’t be overwhelmed by thinking you have to read a lot. Read what is good for you. If you come across too many words and expressions that you don’t recognize, it might be a good idea to find some less challenging reading material. What you read should be challenging, but it should not be so challenging that it might be discouraging.