Your writing should be something you are interested in, not something boring like the history of the pencil. Make sure it's hole-hog , with lots of details.If you have lots of short sentences combine into long ones.
Good writing needs to be clear (English not gibberish ) , with clear beginings middles and ends. Again lots of details (tell me mores).don't repeat words a lot .and make normal ,plain words into creative sophisticated ones.
Write in an interesting way that keeps the writer wanting more, every writer has a unique way of writing (voice).Follow the grammar rules.Also use other people to make sure it makes sense.