I'm really interested in religious History, music History, and Chinese history, and will be double majoring in music education and general history as of next semester. My focus leans more towards anthropology, in how it relates to those things, but that's not a possible undergrad degree just because of how the credits overlap.
My adviser is in the music ed department though, and besides telling me that I should try picking up Chinese and Latin (I already know Spanish), that they weren't really aware of much else that I should do, other than (potentially) declaring a concentration in my history degree.
Any advice?
I'm not sure what exactly you're asking. What's your purpose for the question? Are you thinking ahead about graduate school or are you just trying to figure out how to become more learned in your fields of interest? If it's the latter, I don't see what more you can do. You're already a history major, so it's not like you need to take more classes related to your field. The rest just comes down to what classes the history department (or the religious and music departments) provides. Depending on the size of those departments, you might not have too many classes that are specifically associated with your interests, though.
IDK about your program, but I was required to have a broad base. X number of hours of American history, Y number of hours of Asian/African/Latin American history, Z number of hours of premodern vs.modern history. I had to have so many hours at the 200, 300, and 400 levels, etc.
I wouldn't worry about grad school except to do your best, study hard, and prove you can handle the work. And remember, college is a pyramid - BA is broad and general, a base, MA is narrower and more focused in a specific area, and a PH.D. is the tip, unique research into a specific topic in a narrow field.
Enjoy your undergrad now and take a wide range of classes.