I follow something similar to katfireblade. The rules are different for each world I create. For example, in a current WIP, you can trace the same name through the different nations/cultures through its different spellings. Taliah means lake daughter (tal is lake) the iah ending is girl offspring in the root language of some cultures. The next culture over on the map, however, would drop the h. In a more distant culture the name might look entirely different but have a similar sound, or it might look similar but sound different.
The goal is to have a logic behind the conventions and to be consistent.