Some characters I get a rough idea or vague personality in my head, then create them and let the little quirks and details be fleshed out based on events, but generally be set ahead of time before clicking the Create-a-Face.
Some characters Iv'e spawned as "noname" and just seen what happens.
My favorite though, were a mix of that, where I had the luck to have a decent personality in mind, but let the majority of the character's style be based on what skills they have, and who talked to them first/most.
...all the above, I realize, is also a very non-answer. "Both!"
