Start Early: This sounds so redundant (since everyone talks about it), however, I just wanted to mention it because it is vital. I am not someone who can work well under stress (while some people are), so starting my essays early helped me great deal with changing them multiple times and editing them well before sending them to the colleges. Starting early gives you more time into dwelling with the questions well enough.
READ the common app question you are answering carefully. I know this sounds stupid, but answering the question is a MUST. I am speaking from experience. I had initially written my common app essay in one question and after I talked to my supervisor, I realized that I was answering another question, not the one I had intended to do so. The best way to know if you are answering the question correctly is to ask someone to go over your essay (without telling them what the question is) and ask them what they got from the essay. If what they say now aligns with the question, then may be you answered the question well. If not, well gear up and start working on it!
Read through the essay and summarize what each paragraph talks about: If you can read through the essay and summarize what happens in each paragraph, you will be able to figure out if the ideas in the essay flow well. You will also realize if some paragraphs or ideas are redundant or completely unnecessary. Trust me, this helps. I use this while writing my essays at college too! If you can’t tell what the paragraph is about, then pretty obviously, you need to work on that paragraph.
READ ALOUD YOUR ESSAY: This helped me a lot and hopefully will help you as well. Once you finish writing something, just read it aloud to yourself. You will notice where some words sound awkward and where some ideas don’t flow well. You will also realize where you feel confused/bored or irritated almost.
Ask someone to read through your essay: Once you are done doing the steps mentioned above, ask someone to read through the essay thoroughly. Ask them to summarize/what they got from each paragraph and compare that with the initial meaning you had intended to provide in those paragraphs. This will greatly help if you are communicating your ideas well. Ask them at which points they get bored! You don’t want your admission officer to get bored while he/she reads your essay. You can also ask which words/parts don’t flow well and ask for more suggestions!