I'm working on the Goldbergs myself, even though a friend of mine who's a really good teacher told me they were too hard for me. But obviously some of them are easier than others. You might want to start her off with some inventions, or WTC, to get warmed up. But if she insists on going straight to the Goldbergs, at least don't try to do them in order from 1 to 30. In particular, stay away from the ones that were originally written for 2 keyboards.
Roughly in order from easiest to hardest, you might start with: 7, 19, 10, 13, 9, 4, 2, 3, 1, 6, 30, 18... Of course depending on what tempo you want to use.