When it comes to the use of fonts and typography in documents such as resumes or cover letters, most resources will emphasize the fact that you should never use “fancy” fonts and should always stick to basic ones. While this is in fact true to some degree, some people have a tendency to assume that this means you must only use the generic, common ones that are utilized constantly, such as Arial, Times New Roman, Myriad Pro, etc.
From my experience and education in the world of typography and graphic design principles, the best way to approach the intimidating task of choosing the “right” font is with a different perspective for each situation/context in which you will be using it. For example, when creating a resume, obviously you would not want to use a font that is overly decorative or even slightly illegible (script, handwriting, etc) but that does not mean that you should feel obligated to stick to using the basics. You should, however, try to avoid using more than one font in the same document, so as not to interrupt the impression of continuity and unity. When applying for a job, you generally want your resume and cover letter to look clean and professional, but also keep in mind that your potential employer is probably reading a rather large stack of resumes written in the exact font that you probably also used.
The goal is to make your resume stand out and be memorable, and the best way to do that (after ensuring that your resume is well-written/organized and lists your qualifications for the job) is to find an uncommon or custom font that is sans-serif, easily legible, and has a sleek, corporate feel. The person reading your resume does not need to be consciously aware that you used a different font, but choosing one that is slightly unique in a subtle way will be much more likely to allow your resume to “stick” in the memory of the reader, which is always a good thing, especially if the particular position you’re applying for is very sought-after and has a lot of competition.