The essay should be a sequence of paragraphs, each paragraph containing a new thought or idea.
An essay must have a unity, developing one theme with a definite purpose. The subject must be clearly defined in the mind and kept in view throughout.
The paragraphs should be linked together by the unity of thought. There should be a logical development of thoughts and ideas leading to a definite conclusion.
Take a special care to make the beginning interesting. Remember the first paragraph introducing the essay is the most important.