You would dress properly for an interview.
You also use formal language in an essay or research paper.
Follow these guidelines to maintain a formal writing voice in your essays.
1. Do not use first-person pronouns like: “I,” “me,” “my,” “we,” “us.”
2. Avoid addressing readers as “you.”
3. Avoid the use of contractions: say “can not” rather than “can’t.”
4. Avoid slang expressions.
5. Avoid abbreviated versions of words. (TV or photo)
6. Avoid the overuse of short and simple sentences.
Do not confuse formal diction with jargon (the kind of language only familiar to people within a specialized field, such as computer technicians).
You should not sound “artificial” as you use formal diction. Through your word choice in essays, you can portray yourself as an intelligent person who is aware of your audience–a group of well-educated people whom you do not know. (from ivcc)
To read more: http://www2.ivcc.edu/rambo/tip_formal_writing_voice.htm
1. Watch this short video.
2. Use formal language in your paper.