Anyone who does much writing will eventually confront the question of the best way to give emphasis to a particular word or phrase in what they have written. Maybe it’s a desire to attach special significance to part of a quote, or a need to make absolutely sure that the reader doesn’t miss a central point — but the time will come where, to be on the safe side, emphasis must be added.
So, what’s the best way to emphasize the written word? The basic options, currently, are using underlines, italics, or boldface. Some people then use a combination of the three to give even more emphasis. (Back when I first started working, in the days long before social media and texting, some people used all caps to provide emphasis. Now the all-caps look is generally perceived by the reader as screaming, and there’s very little being written about that needs that much emphasis. What you want is for the reader’s internal voice to “think” the word being emphasized just a bit louder than the rest of the text, and not have them mentally screaming like a character in a bad teen horror movie.)
My emphasis tastes vary depending on what I’m writing. For blog entries like this one, I prefer to use italics to give a word that special nudge. For legal briefs, however, where case names are italicized and section headings are in bold print, I tend to use simple underlining to emphasize specific text. That way, there’s no mixing up the message.
And I don’t like using various combinations of bold, italics, and underlining to give extra-special emphasis to certain words or passages. For one thing, I think random mixtures of “emphasis-adders” is confusing to the reader; it suggests that there is some emphasis hierarchy that the readers hasn’t been told about, which may leave them wondering about relative emphasis rather than concentrating on what is written. (“Let’s see — is don’t supposed to get more emphasis than don’t, or is it the other way around?”) And using multiple combinations for some words seems to devalue the words that merit only a single emphasizer. I think emphasis-adders should be used sparingly, and if you’ve got to use combinations you’re probably overdoing emphasis to the point where the message is being lost. You might want to think about editing your sentences to be shorter and clearer, instead. Plus, the use of random combinations of emphasizers makes the printed page look messy, like a riotous fruit salad.
So, my rule of thumb on adding emphasis is to stick to one — and only one — technique, and to use it sparingly. If you write clearly, you’ll be just fine with that.