To improve English(or any other language) I believe it is very useful to copy, or at least implement, what others have said or written.
By that I mean that you could copy phrases or ways of speaking directly into your own writing. Let's say you want to make a dialogue and want to make it sound natural. Then you could listen to how someone on the east coast speak and someone elsewhere uses English and use that to make your two characters. People on the west cost speak a little different than people on the east coat. They just use the words slightly differently. How can a painter paint a tree or a rainbow, if he has never really seen one? How can you write well if you do not study how others use the language? Copy what others have written or said, and use it in your writing. Change it, manipulate it, work with it for learning and inspiration. Again, I'm not saying copy works, but sentences, phrases, or clauses etc. Today I heard someone using the expression that something someone spoke to her was 'hitting her soul.' I've never heard that expression before. Why not use it? To improve your writing you have to use raw material in your writing, and not just reading it. Because you learn to write by actually writing. Books are filled with excellent sentences that describe things, explain things; words that 'hits the soul of the reader.' Take them out of their context and use them in your own. By imitating others, you would be surprised how much you can actually say and how good it sounds. By imitating others, you will never run out of words or ways to say what you want to say. Learning a new language is difficult; you don't need to reinvent the wheel as well.