All right, I’ll admit it: this is a case of “it takes one to know one.” And to be honest, I look at some of my earlier novels and short stories and cringe. I’m an educated middle-class intelligent white woman; all my characters sound like educated middle-class intelligent white women. How bland can you get?
Once I had this problem pointed out to me, I started listening to people more attentively. All writers are eavesdroppers; but we generally eavesdrop for content, not delivery. Yet if you spend some time listening to how people talk rather than what they say, your characterizations will benefit from it enormously.
For example, listen to American teenagers sometime (one of them lives with me, so I have a fair number of opportunities to hear this particular flavor of English), and you’ll hear something like this:
I’m like talking to her, right, and then suddenly she’s, like, I’ve heard this already, right, and I’m like, I don’t care…
The person who helped me select paint down at the hardware store on Commercial Street was a second-person sort of narrator:
You want to give this one two, maybe even three coats. You prime it and you do another coat and then you wait. You wait for the right color to show up, that’s when you know not to paint no more.
Certain occupations tend to call for an excess of courtesy in language if not always in deed. Get pulled over and you’ll observe how the police talk; my friend Steve, who used to be in the army, has the same habit.
Yes, ma’am, that’s correct. Ma’am, you need to step over here. No, sir, I didn’t ask you to step over there…
Individuals tend to find expressions they like and stick with them. Many people will use the phrase “I’m just saying,” as a way to segue into a repetition of a statement they just made (and as a way of not listening to anyone else’s opinion on the subject!); I used it in my play Tokens of Affection to give a character wrapped up in herself a way to show it verbally. I expect that you could make a list of similar verbal crutches used by those around you. Ask yourself what those verbal crutches do for the individual, so that when one of your characters needs that, you’ll have the expression to hand.
Want to find out how people sounded (at least in the United States) at different times and in different places? The Library of Congress at memory.loc.gov is where you want to go.
A word of caution: don’t perpetuate stereotypes! For example, people from the northern US states tend to unfairly think that the drawling rhythm of “southern” speech denotes someone who is a redneck, slow, or both; don’t fall into that trap. It’s a lot of -isms that you really don’t want to be part of … and it’s rarely accurate. Characters who are fresh and interesting are characters whose authors have gone deeper than the surface in creating them.
When you’re getting to know your characters, assign each of them a phrase or pet expression to use; it will go miles toward showing rather than telling what that person is all about. And when you’re out and about, listen to how people talk — it will keep giving you fresh ways for your characters to express themselves.
And then you’ll be … beyond the elements of style!