I am taking a class that covers art in Florence, and I am extremely surprised by how much I already know about this subject. I studied music, but I have never taken a class in art history before. I approach art in this way--
1. I go to places where there is art.
2. I walk around and look at the art. I don't do audio tours or guides unless I am forced to. Only occasionally do I read the placards and then mainly to see the dates and names of the artists.
3. I look until I see something I like and I buy a postcard of it. Often the one I like doesn't have a postcard.
4. I go home and learn about the stuff I liked. I go to exhibits of stuff I like. Eventually I like more things.
That's it. This approach can be used for music, too, just not for professionals.