If I remember correctly, on the underside of your wrist is your actual shade of skin color so you are suppose to test the foundation there to get the right shade for you face. This is obviously when you don't have a tan. If you have a tan, yeah, you need to match up the tan color.
For some people, they have to mix two colors to get the right shade, but, that is mostly for people with fair skin, and she clearly has skin color, so she doesn't have to worry about that.
I hate foundation myself and don't wear it. If I have a blemish, meh, people will just have to deal with it, lulz.
Anyway, if she is possibly self-conscience, she should probably avoid the orange look because people will stare and judge, lol.
I think you posted a pic of her without make up and she looked fine