When you're picking personalities for minor NPCs, it helps to remember that cliches become cliche because they work so well. They're only tiresome when creators try to save on effort by only lightly sketching in the most surface details. Done with any amount of genuine effort they quickly remind you why they're so popular. It's like the difference between a remix of a classic song that both reminds you what you loved about the original and introduces enough new flourishes to entertain, and someone who can only sing the chorus and just hums "da-dah-dah-da" in between.
So throw some cliches at them. The earnest young kid on his first real job, the lamed veteran looking for an easy gig till retirement, the guy with a shady background who's trying to reform, the woman who seems really eager for a night job and avoids questions about her past. See which ones the players bite on. Then you can put in the trouble of fleshing that one out some more.