You might not be a professional designer or have a degree on typography, but you should do your best to make your resume readable, clean, nice looking and modern. Commonly used fonts that are outdated like Times New Roman (or worse, Comic Sans) make your resume look super tacky.
In an attempt to comply with the “one-page rule” I’ve seen many applicants make fonts tiny, margins smaller and remove most of the spacing between lines and paragraphs, squashing all the content into a single page. That’s not the point, and it doesn’t make your resume easier to read or skim. In fact, it does the exact opposite.