Do you listen to your writing? Probably the best way to listen is to read it aloud. Sometimes when you read silently, you might not realize the number of times the word that or therefore or however appears in a one-page essay. You may be using those words correctly, but the repetitiveness will not keep the reader riveted to every message you’re trying to convey.
I challenge you to draft an essay. When you are close to writing the last draft, read it aloud. Then, search and find any word or words that you have repeated more than once in the first two sentences or the first paragraph. Once you notice that perhaps you have that appearing at least 10 times in a one-page essay, open a thesaurus and search for ways to replace some of your words or find ways to revise your sentences.
For transitions words, such as therefore, I recommend reading our fairly comprehensive list of transition words and phrases. Be sure to review our extensive library of Grammar & Writing resources. By the way, all transition words need not be put at the beginning of a sentence. You can weave them into the sentence after a few words.