1. Read, read, and read.
The more you read especially novels and literary works, but also magazines and newspapers - the more words you'll be exposed to. As you read and uncover new words, use a combination of attempting to derive meaning from the context of the sentence as well as from looking up the definition in a dictionary.
2. Keep a dictionary and thesaurus handy.
Use whatever versions you prefer in print, software, or online. When you uncover a new word, look it up in the dictionary to get both its pronunciation and its meaning(s). Next, go to the thesaurus and find similar words and phrases and their opposites (synonyms and antonyms, respectively) and learn the nuances among the words.
3. Use a journal.
It's a good idea to keep a running list of the new words you discover so that you can refer back to the list and slowly build them into your everyday vocabulary. Plus, keeping a journal of all your new words can provide positive reinforcement for learning even more words - especially when you can see how many new words you've already learned.
4. Learn a word a day.
Using a word-a-day calendar or Website or developing your own list of words to learn is a great technique many people use to learn new words. This approach may be too rigid for some, so even if you do use this method, don't feel you must learn a new word every day.
5. Go back to your roots.
One of the most powerful tools for learning new words and for deciphering the meaning of other new words is studying Latin and Greek roots. Latin and Greek elements (prefixes, roots, and suffixes) are a significant part of the English language and a great tool for learning new words.
6. Play some games.
Word games that challenge you and help you discover new meanings and new words are a great and fun tool in your quest for expanding your vocabulary. Examples include crossword puzzles, anagrams, word jumble, Scrabble, and Boggle.
7. Engage in conversations.
Simply talking with other people can help you learn discover new words. As with reading, once you hear a new word, remember to jot it down so that you can study it later and then slowly add the new word to your vocabulary.