Very randomly, by mixing the names of old coworkers, names from baby name websites, or names I jot down from other places. 🤷♀️ My goal, not always achieved, would be for them to sound slightly unusual, sophisticated, and like they fit in a fantasy world, and not be distracting in some way (like accidentally being a celebrity...)
If the person's name will appear in a puzzle, especially if that's before it appears in an article (something I'm moving away from now), I try to use a word surname or a very recognizable name so it's more solvable. I don't usually pick names based on symbolic meaning, because that feels too gimmicky - like I wouldn't name a gardener Florian. (There is one matching pair of names for two connected characters, which could be seen as a gimmick, though. 🕵️♂️)
I really underestimated how many names I'd have to come up for this project, thanks to the newspaper format, so it's been a work in progress! Thanks for the interest. 🙂