Art history class can be challenging. Some times the teachers do not make the situation better. They spend a lot of time on the art forgetting that the course is a combination of both.
To do well on this course, I will advice that you take lots of notes, teachers of the course talk a lot. Write down all important statement made. Do further studies on the art, spend time to read, practice how to talk and write art.
If you do all of these, I believe the course will be a lot easier for you.