Guidelines for place names, people names

I can't seem to find any official guidelines for family tree data entry.

One of my questions concerns place names. Should I enter the modern name or the name of the place when the event occurred?

If a person was known by multiple name throughout their life, I know that you can have "alternate names", but how do you decide which name to set as the "main" name? I have been using the name I *think* that person would have perferred or thought of themself as.

Thank you so much!