spanish, english and mandarin are really useful languages to have.
Learn logic, it is not only useful but essential, for this you might wanna study some programming logic.
Electronics Is always useful, organic agriculture Is even more useful.
Study body language.
Learn how to proprietly speak to a croud, critical thinking and logical fallacies.
Learn how to be a good teacher for this you might wanna study psychology and analize some manipulation Tactics.
Learn to analize.
Those are some things that come to mind.