For a intermediate learner such as yourself, I would suggest reading a lot. Reading English books, as well as the newspaper, will help to expand your vocabulary and give you examples of English writing in a professional manner.
I would also recommend reading something out loud, with an eye on your pronunciation. You can get an audiobook, and read it out loud. Then, you can listen to how the speaker says it. Try to mimic their pronunciation. You will notice your pronunciation get better.