In Zelda/Pokemon games I'll usually use my real name, or the name "Spim" which I randomly typed into Ocarina of Time one day and really liked the way it looked, so I've been using it for the last 13 or so years in various games, usually on a second playthrough (after using my real name the first time).

In FF games, on my first playthrough I'll use whatever the default names are, changing TERRA to Terra if necessary. On subsequent playthroughs, if I change the names, I'll use a group of names that all go together. For example, on one playthrough of FF6 I used names of Futurama characters (Fry, Leela, etc), trying to pick names that sort of matched the FF6 characters. Sometimes I'm just lazy, though.