Since taking up voice acting I have been paying close attention to accents. Some accents are from the way people pronounce words, I.E. the Scottish and Spanish burr or rolling of the r.
However, I was listening to a friend from Germany via Britain and realized that her pronunciation of words was correct according to 'standard' American English. The accent came from the use of vocal muscles that are not normally used here. I have noticed this with other people. The pronunciation is what we consider correct but the sound is different. Different languages and dialects use different muscles to speak.
The trick then is to develop those muscles. At least that is what I think.