It depends on what you want to focus on. There are many types of books that present different situations that a foreigner might experience in a different country. For example:
"Get a room at this hotel in English."
"Order drinks for you and your friends in English." etc.
But if you just want to improve your written English in general, I recommend you keep a daily journal. Talk about what you did that day and/or write down your thoughts. Try to write at least one paragraph per day. Get a language partner who will go through your journal entries with you once or twice a week and explain everything you did right and wrong.