Otra vez vs. de nuevo

[ItsThaMonsta]

They both mean "again". Any common rules for this?

[Rusty]

I believe these are completely interchangeable, but only when they are the correct translation of the English word again.

For instance, when you've done something, and then do it again, volver a can be used, as can the adverbs nuevamente or repetidamente. (It's also OK to use otra vez and de nuevo as the adverbs.)

Sometimes the word again appears in phrases that are idiomatic, so it's important to use the correct translation. For example:
again and again = una y otra vez
now and again = de vez en cuando
never again = nunca más/jamás
once again = otra vez
you can say that again = ya lo creo