A college student is expected to be proficient in paper writing, such that he (or she) will learn new words during his (or her) few years in the university. The expectations are higher for students of the English Department, as a literary career can be one of their options. The admissions tutor isn't paying too much attention to the applicant's vocabulary (or the lack of), as the applicant's first attempt at literary criticism matters most. The same thing applies to the first essay paper. A BA English student (or someone pursuing a dual degree) may not get away with the same excuse next time.
You have your own experience on learning new words during your high school days, when you struggle to understand Elizabethan English. You're familiar with some classical novels, but you look to Cliff Notes for guidance. And you rather watch a Hollywood production of a Charles Dickens's book. All of these don't fall under literary criticism, as you should be able to do more than those tasks. A wide array of words will enable you to write your best argument, which would impress your professor. It's a lifelong process if you're dedicated to the craft, but you're unaware about it during your first year. You have requirements to meet, and you don't want to miss the deadline.
In this digital age, you only need a computer screen and WiFi connection. An online dictionary site must be accessed in seconds. It also helps if you have another website that refers to synonyms and antonyms. If you can find another site that defines certain phrases and/or idioms, then it will be much better. This is the first step.
Slow and Steady Wins the Race
Reading must be part of your daily routine. This might be the toughest thing to do especially what happened last Christmas. You almost missed the deadline on two or three occasions, but your persistence gave you the much-needed adrenaline rush during that unholy hour. There won't be any repeat if you read during your free time. It seems like a big part of you is giving up for something that is far from fun and fulfilling. It can cause problems if you're not aspiring for authorship. Your professor will appreciate the effort you put into your paper if you can come up with different adjectives, such that you won't use the same word over and over again. This can affect your professor's attention on your assignment, as a low mark can be a bummer. Think of the hard work that you put into it, which is why you have to give it your best effort.
Think like a journalist. You should know that news writers don't use archaic words, as it must be important that their readers understand the feature after going through the first paragraph. They may have resort to simple words (except for technical terms that are unavoidable if the subject pertains to a particular field), but it's not like the news writer has a limited vocabulary. Keep in mind that news writers work under pressure, so there may be no time to consult a dictionary. Don't be surprised if most of them have a paperback behind their table, which they read whenever there's nothing else to do. Reading enables them to recall words (without consulting a dictionary). And they manage to keep it short and simple. The same principle applies to essay writing, but literary criticism requires several pages.
Pay attention to what you read between the lines. You'll figure out that it's fine to use the passive voice every now and then, as long as you want a shift of tone in the narrative. You become familiar with the different kinds of figure of speech, which you can apply to your essay assignments. (Your professors won't be impressed with frequent use of simile and metaphor, though.) You've been warned about long, complex sentences. You have a good excuse to use it, as long as you can describe something (or someone) precisely. Your choice use of words will help you avoid the common pitfalls associated with it.
Avoid the Following
You're not writing an essay to impress your professor. In this regard, the frequent use of archaic words is not advisable in most cases. Use simple words, as there's no need to make paper writing more difficult for you. Stating a message, loud and clear, is more important than your expansion of vocabulary.
Words must express an idea, if not a thought, but a sentence can make a powerful statement. A paragraph can grab your professor's attention right away. This is not a cue to look for words seldom used by most readers. It comes down to self-expression, so how you write it will matter most.
If you're uncertain of using a particular word, then don't use it at all. Make sure that you understand the meaning completely. The next thing to do is to say it loudly, using it in a sentence. Repeat it until you figure it out if it sounds natural. Look for another word if you're not satisfied at all.
Looking at a dictionary can be a time-consuming activity, so do it on a minimum while you try to finish your assignment. Don't forget to look at it when you're getting bored during an uneventful weekend.
Don't think about vocabulary when you're doing errands. There's the right time (and a right place) for it. Some students insist on night time, though.