To stand out in any job application, you are usually going to need a covering letter. This is your way of explaining why you want the job, what you can bring to it and how your skills would be relevant. It allows you to add more than just sending in a CV, which is why this part of an application is so important.
The most important thing is to make sure your cover letter is written eloquently and professionally, meaning no spelling or grammar mistakes. These will make you stand out for all the wrong reasons. Ask someone else to proofread your application before you send it in.
Be concise – nobody wants a cover letter that is too long. At the same time, make sure all the important points are in there and you have written enough to sell yourself. Employers want to know what you are like and what drives you, so make sure this comes across.