I edit many "academic essays". There are a few weaknesses which recur, no matter who the author is. One such weakness is the use of (anaphoric) pronouns -- pronouns which refer to someone or something elsewhere in the text. Pronouns should not need too much effort by the reader to know what they are referring to. Supposing you should write: "And that, they say, is how it is." What then is "that"? Who are "they"? And so on. All such pronouns need clearly to refer to something or someone. OBSERVATION: Not to speak of that something or someone being clear in themselves.