Vocabulary is the cornerstone of your foreign language skills. Without a large vocabulary, even the best understanding of foreign language grammar will not allow you to speak. Read, read, and read. The more you read - especially novels and literary works - 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. It won't be an easy project, but you'll learn a lot.