Pay attention to the words you speak and double check that you're using them correctly. Create a foundation for higher English with a correct pattern of regular English.
Use a spell check or dictionary when you type on the computer to insure you're learning how to spell the most commonly used words in the English language. Spelling everyday English correctly allows you to use more difficult words.
Use a thesaurus to replace words you use often with words that mean the same thing, yet are at a higher vernacular. Begin to incorporate these words into your everyday speech.
Write down words you hear that you don't recognize. When you're at home, look up the definitions to the words. Learn how to use the word, say it correctly, and spell it. Incorporate the word into your speech.
Listen to literary volumes on tape or CD. Books like Crime and Punishment, Jane Eyre, and Pride and Prejudice contain language not usually used today. Keep a notebook of words you don't recognize or use currently. Look them up, learn how to say, spell, and use them, and then incorporate them into your speech patterns.
Avoid slang and jargon. Slang, along with colloquialisms, is considered to be lower English, and is usually used to explain something that you can use higher English words to explain. Jargon is only considered high English if it's jargon in a field in which you have studied.
Take a grammar class to learn rules for using the English you already know in a higher manner. Placing the preposition at the end of the word, splitting modifiers, and using incorrectly placed verbs and nouns all make you read and sound as if you're using a lower form of English. Once you learn how to write and speak in grammatically correct ways, the English you already know will be much higher.