I think I have the same kind of question :) And I think the answer is just to read/listen specialized literature (if we are talking about not having a good vocabulary in terms of words). But if we're talking about being able to express yourself as precise as in native language -- I think it's not easy. I mean, sometimes it's easier for me to say what I mean in English, than in Russian (it just fits better). So, I guess, the only real answer would be to read more _descriptive_ literature, and focus on details. I think reading the chapter and trying to pick a moment (for example, description of the room of main character) and try to describe it with all the details that were there (i think it's better to write it, than to say, because you will be able to see the result of what you can actually express). If you forgot the word, you might put a gap/or search for it (by describing it) online in English/or put word in Russian. This way, you will actually see how far you are in terms of details from what you want to say and what you can say; plus you will build up the _active_ vocabulary, by trying to use these words when describing things yourself. Because, the main reason, I guess, why it's hard to talk in a very descriptive way, is because a lot of things are in our passive vocabulary and not active one. I think it's really hard in terms of learning, but I am pretty sure it is the only way. And of course it's not done over the night. I think what you mean here is not even C1 level, it's more like C2+ :) I hope you'll find these advice helpful! In fact, since it's a boring thing to do, maybe we can be a study partners :)