It is your chance to stand out and draw attention to your skills, especially those that haven't already been addressed. Saying "because I need a job" or "I'm really good" just won't cut it. Don't speculate about other candidates and their possible strengths or flaws. Make sure you focus on you. Explain why you make a good employee, why you are a good fit for the job and the company and what you can offer.

Keep it succinct and highlight your achievements.