After you have written something, there are several steps you should follow in order to produce your best writing;
- Use your spelling/grammar check software to catch any obvious errors.
- Correct the mistakes.
- Read your work carefully, looking for misspellings, wrong Word choices, and places that don't make sense.
- Correct everything again.
- Have someone else read your work - a friend or family member or teacher if you can't afford a professional editor.
- Make any corrections they spot.
That's known as editing and rewriting. It's easy but boring.