I think that some words are only used in the written language, but if you speak it out, others will ask you "what?" Examples are words in SAT. But for the words that are used in speaking, try to use it in your everyday life. Do you use English in your working environment? If not, try to use it in written English first, e.g. in personal emails, and then when the chance comes that you need to say things, the word will be at your tongue.