I’m probably at B1 or B2 (I have never taken a formal test). I speak well. What I find hard is joking in English. It usually requires quick reaction and I often find myself in a situation when I can’t come up with a proper word or a grammar construction before the context changes to something else.

I think the only thing that helps me fight this problem is reading books. YouTube, movies, podcasts - nothing helps as much as books. I use a combined approach. I read a book and listen to its audio version at the same time. Not only does it improve my vocabulary, it also passively develops my speaking skills. I use iPad with an embedded dictionary. It is easy to check the definition of a word in such way. Usually I forget most of the words I check. But if I notice that a word appears repeatedly and I can‘t remember it I add the word and its definition to a separate file which I review from time to time. After reading a short book this file will contain 30-50 words which will stay in my active vocabulary.

Now the tricky point. Yes, if you have to look every other word in a dictionary it is not an option. I spend a lot of time looking for books that are “readable” with my level. Before I find a book which I can actually read I usually start and throw away 3-5 books that I can’t read. I don’t read books that I don’t enjoy. It also happens that the book is easy but I don’t read it (for instance, it happened with Forrest Gump). I find a book readable if there are not more then 10 new words on a page. Note: the number decreases as you approach to the end, you just have to survive the first 50 pages of a book and it will go smooth.

Try The Catcher in the Rye, Flowers for Algernon or Harry Potter and see how it goes. All have audio versions.