I have to specify in my syllabus that the options for the fonts on their papers are Arial or Times New Roman. I recommend Arial. They can use Times New Roman, but the more clever students pick up on the clue that using the font the instructor prefers is much more likely to sell your thoughts in the most positive light. I have had too many students use fonts more appropriate for a wedding announcement, because they thought if their thoughts looked "pretty" it would be more impressive to the reader. No, it is more difficult to read, more irritating, and therefore less prone to give credit. I clarify on the first day of class that readability and professional look (OK, that also means no Comic Sans) are the most important aspects selling your thoughts.
I also tell them no gratuitous clip art. Flowers and butterflies do not help sell your point.
I also tell them no gratuitous clip art. Flowers and butterflies do not help sell your point.