The most obvious way to improve your Spanish vocabulary is through memorization and practice. You cannot avoid memorizing words — it's the only sure way of increasing your vocabulary, and you won't be able to assimilate these words if you don't practice using them. However, additional strategies are available to you as well. For instance, by learning the meanings of common prefixes and suffixes, you'll be able to understand many more words than you have committed to memory. If you know that cantar means “to sing,” and you know that -ción is a suffix equivalent to the English “-tion” and may be used to turn verbs into nouns, you might be able to guess that canción means “song.”