A contrast or discrepancy between what is said and what is meant or between what happens and what is expected to happen in life and in literature. In verbal irony, characters say the opposite of what they mean. In irony of circumstance or situation, the opposite of what is expected occurs. In dramatic irony, a character speaks in ignorance of a situation or event known to the audience or to the other characters. Flannery O'Connor's short stories employ all these forms of irony, as does Poe's "Cask of Amontillado."
Use a reasonably-sized font: either 10 characters per inch or a 12 point font. And choose a font that is easy to read rather one that is decorative: "Arial," "Lucida," "Modern," "Palermo" or "Times New Roman" are some good choices. Scripted fonts are hard to read even if they do make your paper "look nice"; it is the content of the paper that is most important, and making it easy for your readers to understand that content is always a good choice.