Before you submit you should review your final draft. The main areas to consider are:
An essay with excellent content can be let-down by poor grammar, spelling, punctuation, page numbering etc. Make sure that you proof-read your final draft before submitting. If you are not confident about these matters then ask someone else to proof-read for you.
Essay Structure And Flow
Check the order of your paragraphs. Have you presented them in the most persuasive order? Have you put your strongest arguments first? If you are describing a process, you may want to reflect the order in which the process occurs. Have you used appropriate signposting words to make the essay flow well.
Re-read Your Assignment Brief
Have you answered the question? Is the title correct? Have you followed the instructions correctly?
Evidence And References
Have enough sources been included to support your arguments? Are all of your sources referenced properly in the style required?