I am a student of engineering and i started my English practice from two years before. During this time i tried to gather vocabulary to shape my English but i failed because we do not have so many subjects to talk about in a typical day. One day one of my mentors told us, I and my friends were IELTS student, that we had to choose different topics for our practice and that was why we collected topics from Internet, not questions around those topics.
I found using vocabulary in effective way one of the art of a language. For that kind of skill we do need to learn vocab from renowned dictionary because of definition not meaning and using arena where it is perfect to use.