I'm a native speaker of both since I was exposed to both since birth. But since I was born and raised in America, I grew up speaking mainly English (with a hint of surfer dude, but you can't tell online ^o~). I only speak in half Spanish to my mom though, and total Spanish to Spanish speakers. But if I know they speak English, then I'll speak that instead.

Japanese pronunciation is super easy since you only have pure syllables. The only time I have a problem is when you have "nr" together, like in "kunren". The easiest way for me to say it is "kunlen" which, even though is off from the correct pronunciation, it won't be caught by Japanese people since they can't differentiate between the r & l.

I think it's pretty awesome that you want to study all three!

Haha, thanks! I'm using the fact that Korean and Japanese are kind of similar to my advantage since they're both Subject Object Verb languages. And Chinese grammar is OVS like English (which I guess helps... in a way... but it doesn't make it any easier yet =/).