Get yourself a dictionary or thesaurus handy. Depending on your convenience, you can either go for a physical version of the dictionary and thesaurus, or a digital one. The key here is to have an easy access to new words and their pronunciation. Also take a look at the opposite of new words that you come across in order to get a better grasp of their meaning, thus making it easier for you to incorporate them in your conversations and writing.
Pick five new words at random from the dictionary, read and understand their meaning thoroughly. Also take a look at their synonyms and antonyms to get an even better idea of what a word means. You can either make the selection of five words alphabetically, or you can pick them randomly.
Once you understand the meaning of a word, it is also important to understand and learn its usage. Make five sentences each of every word that you have chosen for the day so that you increase your retention of those words.
Continue with the practice day after day until you go through the entire dictionary.
Try to play word games such as scrabble to learn new words and thus enhance your vocabulary. Be careful though, as there are certain words allowed in scrabble that are neither used nor understood by a lot of people.
Try to read digests and magazines as much as you can. There are some excellent digests such as Reader’s Digest that has some excellent content. To top it all, it also has a section “Word Power” that presents a series of new words for the reader to learn.
Make it a habit to read newspaper everyday.