Here are some very common mistakes and problems that I see in many essays, so I want to help you realize these errors and show you how to correct them so that you can improve the quality of your English writing.
1. In formal English writing, you should never use contractions. Contractions are shortened forms of two individual words separated by an apostrophe. Words like "don’t" or "won’t" or "I’d" or "I’ll" should ALWAYS be spelled completely in a formal document. If you use a contraction, it implies to the reader that you are either too lazy to spell out the words or you do not realize that contractions are informal. Therefore, always fully spell out any contractions such as "do not" or "will not" or "I would" or "I will" in your formal essays. This is a skill of a good English writer, so making sure that you avoid contractions will improve the quality and professionalism of your essay.
2. In formal English writing, you should never start the first word of a sentence with a conjunction. Conjunctions are words typically used to combine two shorter parts of sentences together, so they will always only be found inside a sentence. Words such as "because, or, however, and" are the most common examples of conjunctions, which many people use informally as the first word in a sentence, but should never begin a sentence in formal writing. Therefore, your sentences are not academically correct if you say "Because I worked so hard, I received a promotion. And I did it with great care." These phrases should be written correctly by either replacing the conjunction or by rearranging the sentence structure so that the conjunction is within the sentence. For example, a corrected sentence might be rewritten as: "Since I worked so hard and did it carefully, I received a promotion." Alternatively it can also be rewritten as "I received a promotion because I worked so hard and did it with great care." There are many different ways to say the same idea without starting the sentence with a conjunction. In reality, many native English speakers do not know all the proper grammar rules and often write and speak poorly, but school officials expect perfect essays, so you must do your best job to impress them with your English writing ability.
3. Ending a sentence in a preposition is never grammatically correct. Prepositions are words that are placed before a substantive and refer to the relation of that substantive with regards to a verb, an adjective, or another substantive. To explain it more simply, a proposition refers to another word, so if you place it at the end of the sentence, then there is no other word as its reference. I know that sounds confusing, so some examples of prepositions are words like "up, down, to, for, from, at, by" which should never be the last word in your sentence. Therefore some examples of grammatically incorrect sentences are: "I studied hard so my scores went up" or "We traveled for three kilometers, so it showed the teacher how far we came from" or "There is no other class which it compares to." All of those sentences are grammatically incorrect because they end in a proposition. There are various ways to correctly revise those same sentences, so they may be rewritten as: "I studied hard so my scores increased" or "We traveled for three kilometers, so it showed the teacher from how far we came" or "There is no other class to which it compares."
4. One major complication in English is homophones. Homophones are words that sound the same when spoken but are written differently and have different meanings. Very often when I revise essays, I notice misuse of certain words. The best advice is to check an English dictionary if you are unsure if there are alternate meanings and spellings for a word that you want to use. When you use a word incorrectly, the entire meaning of the sentence is wrong. Even worse, the reader who is usually an admissions official with excellent English skill will see the mistake and distract their attention from the content of your paper and draw his attention to the obvious spelling mistake. Examples of homophones are "c, sea, see" or "which, witch" or "there, their" or "weather, whether." Be very aware that although these words sound the same, they have different meanings. For instance, if you write "I went to sea" this means that you went to travel in the ocean. If you write "I went to see" then this means you went to look at something.
5. You need to have parallel sentence structure. Parallel sentence structure refers to using the same verb tense if you state several related sentences or several related issues within the same sentence. For example, it would be incorrect to write "I moved into my house yesterday and the floor is dirty." This is because the word "moved" refers to something that happened in the past, so you must also match that tense to any other verb in the same sentence. To correct this sentence, you must change the entire sentence to past tense because your action happened yesterday. A corrected version would be "I moved into my house yesterday and the floor was dirty." Another incorrect example would be "I often helped my boss arrange books, running errands, contacted customers, and taking phone calls." You must choose a verb tense so that all verbs in that sentence must have the same parallel structure. A corrected version would be "I often helped my boss arrange books, run errands, contact customers, and take phone calls."
6. Another common problem is noun/verb agreement. That is actually a simple issue but people who are not careful often do not realize their mistakes. A noun that refers to one item/person must have a verb that is singular. A noun that refers to several items/persons must have a verb that is plural. Therefore it would be incorrect to write "Stray dogs and cats is a problem in my neighborhood." Since the words "dog and cat" are plural referring to more than one item, then your verb must also be plural. A corrected version would be "Stray dogs and cats are a problem in my neighborhood."
7. Even if you have no page or word limits for your essay, it is always better to be concise. Being concise means that unnecessarily long sentences can be shortened using a different combination of words without changing the meaning or effect of the sentence. For instance, an unnecessarily long sentence might be "Today, after working hard to study all day without stopping my progress, my scores went up a lot." This can be written more professionally and more concise by rewording it as "After continuously studying hard today, my scores increased significantly." By being more concise, you effectively change a sentence from 18 words into a sentence with only 9 words without losing the meaning or effect of the sentence. In this example, you have a 50% reduction in words, which is VERY important if you have a lot of information to say but you have a strict word limit in the essay.
8. To promote your confidence, it is better to state sentences in absolute terms rather than conditional terms. For instance, instead of saying "I believe I can be the best at your school…" you should say "I can be the best at your school…" The first phrase expresses doubt, but the second one expresses confidence. If you are writing an essay for a school application, you want the admissions committee to think that you WILL succeed rather than only THINK you will succeed. People who write confidently are usually more upbeat, ambitious, and successful students, so the admissions committee will look for your confidence to show up in your essay.
9. In formal writing, you should avoid using "passive voice" which are verbs preceded by words such as "have, had…" They indicate an ongoing action, but are not as concise and do not denote as much intent as when you use "active voice." For instance, instead of saying "I have aroused my interests…" you can say "I aroused my interests…" By using "active voice" then it shows intent and active participation which appears more confident rather than passive action that simply happened on its own. In formal business and law documents written in English, "passive voice" is always eliminated as much as possible.
10. Finally when writing essays, especially for those related to your statement of purpose, always try to describe your experiences and what you learned from them. Quite often, I see people write what they did in their school or job, but neglect to mention why that was important. If you only tell the reader what you did but say nothing else about the experience, then that implies you are a follower with no ambition and no ability to improve yourself. For instance, suppose you write "I worked in the bank, collected accounts and worked with customers even though I was quite busy." If this is the only thing you state, then it tells the reader very little about your experience. It appears that you only performed these actions because they were your duties. If you are applying for a school, then the admissions officials will want to know that you have the ability to do something and gain something out of it. That is the reason for education, so that you can experience something in the classroom and learn to apply it. Therefore to improve the essay, you should continue writing something to enhance it, like "Through that experience, I improved my interpersonal skills and learned how to plan and execute projects efficiently."
These are some of the common mistakes that I continuously find in essays that people ask me to revise and edit. In fact, the English language is very complicated and there are hundreds of special spelling and grammar rules that must be followed correctly in order to write a perfect essay. Unfortunately, even many native English speakers only have average writing skills and also make many of these common mistakes. If you want to have an excellent essay, then you should find a very knowledgeable and skilled person who knows how to find and fix English problems. Since I tutored advanced English writing and also studied business and law, all fields require English writing that is concise, persuasive, and accurate. I also worked as an ambassador reviewing new student essays at the University of Michigan, so I understand what a top college wants to see in your statement of purpose.