It surprised me that nobody said to learn the language of your better half... if s/he is not a native English speaker. That way, you have a better family, which is one of the precondition to have a better research life, I guess.
As a Japanese, I would say learning Japanese might help you a bit, because there are many nice math textbooks in Japanese by Kodaira, Sato, Jimbo etc. Yes some of them are translated to English but some of them have not been.
