Use flashcards or computer programs to expand vocabulary. Computer programs can generate sound files to accompany German words to provide correct pronunciation. Flashcards can be homemade or store bought, and practiced at the speaker's leisure. These types of learning devices are great for private practice.
Find a German pen pal for correspondence exchanges. Many German students are learning English, and could use an English-speaking pen pal to improve their English-language skills. Exchanging letters in home languages will benefit both parties. For additional practice, pen pals can write letters in alternating languages, or write different paragraphs in different languages.
Listen to German music for extended vocabulary practice. Choose songs for children or simple folk songs to hear extra vocabulary. Do not choose heavy metal songs, German rap or fast songs, as these types of music will move too quickly for a listener trying to figure out more vocabulary words.