Sentence structure for me >>

English, Japanese, all of the above?

Japanese mainly. though english I never understood either. Which worries me

Understanding the basics of one will help the other, as several aspects are the same across all languages (e.g. basic parts of speech)

We'll see what we can cook up

for me it has to be both sentence structure and not knowing essential words used in communication for said unknown language.

Luciole: If it's Japanese honorifics, see the article on Keigo. Sentence structure articles are under construction as we speak (what pun?)