Read a big interesting book on a historical topic or on life in an exotic country. There will be many archaic or exotic words reflecting items which are not in use anymore or in use only in unfamiliar cultural settings, but it will develop your vocabulary significantly and will provide you with interesting topics for discussion with other people. Very often writers use the same words, phrases or the figures of speech, because people have speech habits. Multiple repetitions by an author will help you to remember unfamiliar words and to sense their appropriate context.
Know the names of the ancient gods; it will help you in maintaining conversation in the arts. Many art masterpieces depict mythological plots and subjects. Learn by heart correct pronunciation of the Greek and Roman gods' names. Also read the Bible, because it is a rich source of inspiration for artists and the reservoir of sayings which have become a familiar part of many cultures.
Write poetry. Although you may not be a poet, thinking about word combinations will help you to feel the nature of a word. Use your poetry works practically. Write short poems to congratulate your friends on their birthdays and weddings. Seek chances to demonstrate your progress and achievements. Finally, searching for a rhyme can be an exciting activity!
Use any opportunity to attend events where an experienced speaker gives a presentation. Use a tape recorder. Make sure you understand the meaning of all the speaker's words. Find unknown words in a dictionary and use them only if their meaning and context of usage are absolutely clear to you.