Determine the style you will be using to write your essay. AP, MLA and APA style manuals dictate how to use and cite interviews. If you're doing the essay for a class, your teacher will tell you which style to use. Typically, AP style works best for interviews used extensively in an essay.
Use a yellow highlighter to highlight the portions of the interview you want to incorporate into your essay. It's important to do this ahead of time so you will have a guideline for laying out your essay. If the essay relies heavily on your interview, place numbers by the highlighted text to show the order you will be using the quotes from the interview.
Write from your highlighted interview. The body of your essay should clearly set up the quote you will be using and lead smoothly into the interview quote. Be careful not to stick a quote from the interview into the body of your essay because it sounds good.
Introduce interview text with "according to," or "Harris states," or other attributions (without quotation marks). Enclose actual interview text in quotation marks with an ellipses before and after the quoted text to indicate missing text from the interview.
Proofread to make sure the quotes you used from your interview don't make up the majority of your essay. The interview quotes are supposed to support your essay, not the other way around. Ensure that the material you used from the interview includes proper citation based on the style guide you're writing to.