I think humor is one of those language areas that is hard to achieve in a foreign language. It seems to me that if you can do that well then you've reached a go

I think humor is one of those language areas that is hard to achieve in a foreign language. It seems to me that if you can do that well then you've reached a good milestone. English idioms are hard, even for native speakers, so you might want to get a book on those. I knew of someone that kept his English sharp by reading whole newspapers every day. You might want to do the same thing by going to one of the big English newspaper sites. The opinion/review area is usually where you will find writers using the more common form of the language. Additionally, to that, I would start a blog or some other writing form that will force you to practice what you've learned on a regular basis. You need to go back and review what you've written and see where you've made mistakes. You might need some help with that. Good luck!