Assign regular reading assignments. Reading is the cornerstone of building vocabulary, and a well-read person almost always has an extensive vocabulary and understanding of words. Find popular books that will appeal to your student and encourage her to read them. Have her underline or highlight any unfamiliar words and review the words and their meanings together.
Use word games to evoke interest. Crosswords, word-searches and jumbles are all fun ways to increase word power. Choose games that are age- and reading-level appropriate to your pupil. Themed word games are a good way to build vocabulary on a particular topic. Find and copy several word games, and do one or two of them each time you meet with him.
Prepare a weekly word list. Have your student look up definitions of each word and write them down. Have her use the word in a sentence that reveals its meaning. Give a weekly spelling test so she can master the word, and have her define it to you in her own terms.
Assign fun homework. Have your student watch Wheel of Fortune and play along, play Scrabble or play word games online like Bookworm. He will come to associate words with fun and become faster at recognizing and spelling words.
Teach her to determine word meanings from context. The next time she reads a sentence with an unfamiliar word, ask her what she thinks the meaning of the word is based on how it's used. Context is a useful tool to determine word definitions if you aren't in a position to look them up.
Teach the meanings of root words, prefixes and suffixes. Once he knows the meaning of several of these, he'll be able to transfer that knowledge and determine a likely meaning for words he isn't familiar with based on the root, prefix or suffix meaning.