My examination essay - what is your biggest mistake

Hi everyone, I am a beginner. I tried to improve my essay and English. I planned to take an examination for a job.
I remember a topic from the last examination, about The biggest mistake. Thanks in advance.

The Biggest Mistake

In the whole of human life have been made a lot of mistakes in there's life. For instance, forget your wallet when you at a cashier, forget to turn off the light in your house, phone to your ex when you get drunk. I have made a lot of mistakes like others but my biggest mistake is not putting an effort enough into studying.

Since I have been studying at college, when I know how does freedom feel like, I did not often keep in touch with my family. Not because I had a lot of classes in or too many activities but because I used to be a game-addict. Every day, after I done with my classes, I always went to the game station and spend my time at least 3 hours per day, It means I was not studying for the exam like a student should be. Until the 1st of junior has passed and the grades were out, I got 1.83 out of 4, my family did not blame me but they always told me 'keep going, We do not care with your grades'. I immediately realized it is time to change. Thus, since 2nd of junior begin. Every single day, I have been studying after classes and bought some textbooks or something I interested in. The result made me satisfied and I never disappoint again. No matter what grades I will get, I am doing the best I can.

In conclusion, I am looking back what is my biggest mistake that I want to change if I could go back in the past. Actually, I think it is a significant and good experience in my life. The mistake made me grow up, face with problems and manage the time effectively.

Cherawit, the first thing you have to learn about writing a narrative essay is that it must have a clear topic presentation in the first paragraph and then a clear development of that discussion throughout the remaining essay paragraphs. In this instance, your grammar could have been forgiven for being so poor if you had only focused your discussion on one topic presentation so that the reader would at least, not feel so stressed while reading the poorly developed sentences. If you pick one topic and stick to providing the supporting discussions for it, then the essay will make more sense to the reader, even if the grammar is questionable. In this instance, the reason the essay became so bad is because your topic for discussion and its related thought process was not clear to the reader.

I think that before you start to write essays, you should first practice developing simple to intermediately complex English sentences. By doing practice exercises for this (the practice tests are free and available online), you will also learn how to properly put together a coherent and cohesive paragraph. Don't aim for the big prize at this point. Start with the small prizes like learning how to develop a properly worded simple English sentence first.

@Holt

I just remembered. The topic presentation is 'what is your biggest mistakes and what did you learn about it?'.
Thank you for your guide. I will keep learning. I really appreciate that.